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ASSET RETIREMENT OBLIGATIONS - Details of AROs Included in the Balance Sheets (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2024 | Dec. 31, 2023
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] |  |
Balance at beginning of year | $ 10,317 | $ 10,840
Liabilities incurred | 130 | 90
Liabilities settled | (566) | (617)
Accretion expense | 400 | 403
Cash flow revisions | (347) | (399)
Balance at end of year | 9,934 | 10,317
Alabama Power |  |
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] |  |
Balance at beginning of year | 4,158 | 4,287
Liabilities incurred | 8 | 0
Liabilities settled | (254) | (270)
Accretion expense | 153 | 156
Cash flow revisions | (7) | (15)
Balance at end of year | 4,058 | 4,158
Georgia Power |  |
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] |  |
Balance at beginning of year | 5,665 | 6,034
Liabilities incurred | 120 | 90
Liabilities settled | (270) | (304)
Accretion expense | 232 | 230
Cash flow revisions | (332) | (385)
Balance at end of year | 5,415 | 5,665
Mississippi Power |  |
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] |  |
Balance at beginning of year | 168 | 179
Liabilities incurred | 0 | 0
Liabilities settled | (17) | (18)
Accretion expense | 5 | 5
Cash flow revisions | (8) | 2
Balance at end of year | 148 | 168
Southern Power |  |
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] |  |
Balance at beginning of year | 150 | 144
Liabilities incurred | 2 | 0
Liabilities settled | 0 | 0
Accretion expense | 7 | 6
Cash flow revisions | 0 | 0
Balance at end of year | $ 159 | $ 150

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- Definition The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 410 -SubTopic 20 -Name Accounting Standards Codification -Section 25 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481999/410-20-25-4 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 410 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481850/410-20-50-1 + Details
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- Definition Amount of accretion expense recognized during the period that is associated with an asset retirement obligation. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 410 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481879/410-20-45-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 410 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(3) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481850/410-20-50-1 + Details
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- Definition Amount of asset retirement obligations incurred during the period. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 410 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481850/410-20-50-1 + Details
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- Definition Amount of asset retirement obligations settled, or otherwise disposed of, during the period. This may include asset retirement obligations transferred to third parties associated with the sale of a long-lived asset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 410 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481850/410-20-50-1 + Details
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- Definition Amount of increase (decrease) in the asset retirement obligation from changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 410 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(4) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481850/410-20-50-1 + Details
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- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
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