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Contingencies - Environmental Remediation (Details) - USD ($) $ in Millions | Sep. 30, 2025 | Dec. 31, 2024
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GEORGIA POWER CO |  |
Loss Contingencies [Line Items] |  |
Environmental remediation liability, current and former sites | $ 13 | $ 13
SOUTHERN Co GAS |  |
Loss Contingencies [Line Items] |  |
Environmental remediation liability, current and former sites | $ 227 | $ 222

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