XML 185 R143.htm IDEA: XBRL DOCUMENT
v3.24.0.1

CONTINGENCIES, COMMITMENTS, AND GUARANTEES - MPC Other Matters (Details) | 12 Months Ended | 60 Months Ended |
--- | --- | --- | ---
Dec. 31, 2023 USD ($) | Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2019 USD ($) | Dec. 31, 2025 USD ($) | Jan. 15, 2024 USD ($) | Jul. 30, 2022 claim
Loss Contingencies [Line Items] |  |  |  |  |  |  |
Period costs | $ 90,000,000 | $ 36,000,000 |  |  |  |  |
Mississippi Power |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |
Period costs | 0 | 0 |  |  |  |  |
Kemper County energy facility assets, net | Mississippi Power |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |
Pre-tax charge to income | 17,000,000 | 15,000,000 | $ 11,000,000 |  |  |  |
After tax charge to income | $ 12,000,000 | $ 12,000,000 | $ 8,000,000 |  |  |  |
Plant Daniel | Mississippi Power |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |
Plant units | claim |  |  |  |  |  |  | 2
Plant Daniel Unit, Primary | Mississippi Power |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |
Plant units | claim |  |  |  |  |  |  | 1
Scenario, Forecast | Kemper County energy facility assets, net | Mississippi Power | Maximum |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |
Period costs |  |  |  |  | $ 15,000,000 |  |
Scenario, Forecast | Plant Daniel | Mississippi Power |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |
Payments to acquire businesses |  |  |  |  |  | $ 1 |
Scenario, Forecast | Plant Daniel | Gulf Power |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |
Percent ownership in individual unit |  |  |  |  |  | 100.00% |
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Gulf Power |  |  |  |  |  |  |
Loss Contingencies [Line Items] |  |  |  |  |  |  |
Proceeds from divestiture of businesses, amount held back |  |  |  | $ 75,000,000 |  |  |

X
- Definition After Tax Charge To Income + References No definition available. + Details
Name: | so_AfterTaxChargeToIncome
Namespace Prefix: | so_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Pre-Tax Charge To Income + References No definition available. + Details
Name: | so_PreTaxChargeToIncome
Namespace Prefix: | so_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Proceeds From Divestiture Of Businesses, Amount Held Back + References No definition available. + Details
Name: | so_ProceedsFromDivestitureOfBusinessesAmountHeldBack
Namespace Prefix: | so_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Public Utilities, Plant Units + References No definition available. + Details
Name: | so_PublicUtilitiesPlantUnits
Namespace Prefix: | so_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Undivided Ownership Interest, Ownership Interest In Individual Unit + References No definition available. + Details
Name: | so_UndividedOwnershipInterestOwnershipInterestInIndividualUnit
Namespace Prefix: | so_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | duration

X
- 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
Name: | us-gaap_AssetRetirementObligationLiabilitiesIncurred
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 460 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482425/460-10-50-3 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 450 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147483076/450-20-50-1 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 450 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147483076/450-20-50-4 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 450 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147483076/450-20-50-4 Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 450 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 9 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147483076/450-20-50-9 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 450 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 9 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147483076/450-20-50-9 + Details
Name: | us-gaap_LossContingenciesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 805 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (b)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479581/805-30-50-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 13 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482740/230-10-45-13 + Details
Name: | us-gaap_PaymentsToAcquireBusinessesGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | dei_LegalEntityAxis=so_MississippiPowerMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilityAxis=so_KemperIgccMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilityAxis=so_PlantDanielUnits1And2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilityAxis=so_PlantDanielUnitPrimaryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementScenarioAxis=srt_ScenarioForecastMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=so_GulfPowerMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DisposalGroupClassificationAxis=us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=so_GulfPowerMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |