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Regulatory Matters - Southern Company Gas (Details) - USD ($) $ in Millions | Jul. 31, 2024 | Jul. 02, 2024 | Jun. 07, 2024
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SOUTHERN Co GAS | SAVE |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Approved investment amount |  |  | $ 355
Approved investment variance amount |  |  | $ 5
Program duration period |  |  | 5 years
SOUTHERN Co GAS | SAVE | 2025 |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Approved investment amount |  |  | $ 70
SOUTHERN Co GAS | SAVE | 2026 |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Approved investment amount |  |  | 70
SOUTHERN Co GAS | SAVE | 2027 |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Approved investment amount |  |  | 70
SOUTHERN Co GAS | SAVE | 2028 |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Approved investment amount |  |  | 70
SOUTHERN Co GAS | SAVE | 2029 |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Approved investment amount |  |  | $ 70
Atlanta Gas Light | Subsequent Event |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Recovery of capital investments |  | $ 600 |
Approved rate increase (decrease) | $ 120 |  |

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