XML 164 R122.htm IDEA: XBRL DOCUMENT
v3.24.0.1

REGULATORY MATTERS - GPC Regulatory Matters (Details) - USD ($) $ in Millions |  |  |  |  |  |  |  | 1 Months Ended | 6 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Mar. 24, 2024 | Oct. 17, 2023 | Oct. 05, 2023 | Jan. 01, 2021 | Jan. 01, 2020 | Jan. 01, 2018 | Jan. 01, 2016 | Dec. 31, 2022 | Jun. 30, 2021 | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2009 | Jan. 31, 2018 | Dec. 31, 2016
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net regulatory assets |  |  |  |  |  |  |  | $ 5,833 |  |  | $ 6,523 | $ 5,833 |  |  |  |
Deferred Income Tax Charges |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net regulatory assets |  |  |  |  |  |  |  | 866 |  |  | 897 | 866 |  |  |  |
Georgia Power |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net regulatory assets |  |  |  |  |  |  |  | 4,663 |  |  | 5,090 | 4,663 |  |  |  |
Georgia Power | Deferred Income Tax Charges |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net regulatory assets |  |  |  |  |  |  |  | 583 |  |  | 605 | 583 |  |  |  |
Plant Vogtle Units 3 and 4 | Georgia Power |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Estimated in-service capital cost |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 4,418 |  |
Proceeds from recovery of financing costs |  |  |  |  |  |  |  |  |  |  | $ 3,000 |  |  |  |  |
Project capital cost forecast |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 7,300 |
Requested decrease in NCCR tariff |  |  |  |  |  |  |  | $ (36) |  |  |  |  |  |  |  |
Additional construction capital costs |  | $ 17 | $ 308 |  |  |  |  |  |  |  |  |  |  |  |  |
Retail rate of return on common equity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10.95%
Authorized ROE |  |  |  | 5.30% | 8.30% | 10.00% | 10.00% |  |  |  |  |  |  |  |  |
Potential decrease each month, percentage |  |  |  |  |  |  |  |  |  |  | 0.10% |  |  |  |  |
Return on equity reduction, negative impact on earnings |  |  |  |  |  |  |  |  |  |  | $ 310 | $ 300 | $ 270 |  |  |
Plant Vogtle Units 3 and 4 | Georgia Power | Deferred Income Tax Charge, Debt Component |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net regulatory assets |  |  |  |  |  |  |  |  |  |  | 14 |  |  |  |  |
Plant Vogtle Units 3 and 4 | Georgia Power | Deferred Income Tax Charges |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net regulatory assets |  |  |  |  |  |  |  |  |  |  | 17 |  |  |  |  |
Plant Vogtle Units 3 and 4 | Georgia Power | Deferred Income Tax Charge, Equity Component |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net regulatory assets |  |  |  |  |  |  |  |  |  |  | $ 23 |  |  |  |  |
Plant Vogtle Units 3 and 4 | Georgia Power | Twenty Fifth Vogtle Construction Monitoring Report |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum guarantee |  |  |  |  |  |  |  |  | $ 1,700 |  |  |  |  |  |  |
Customer refund |  |  |  |  |  |  |  |  | $ 188 |  |  |  |  |  |  |
Plant Vogtle Units 3 and 4 | Georgia Power | Scenario, Forecast |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Return on equity reduction, negative impact on earnings | $ 30 |  |  |  |  |  |  |  |  | $ 90 |  |  |  |  |  |

X
- Definition Additional Construction Capital Costs + References No definition available. + Details
Name: | so_AdditionalConstructionCapitalCosts
Namespace Prefix: | so_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Cost Settlement Agreement Revised Forecast, Net Of Payments + References No definition available. + Details
Name: | so_CostSettlementAgreementRevisedForecastNetOfPayments
Namespace Prefix: | so_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Customer Refund + References No definition available. + Details
Name: | so_CustomerRefund
Namespace Prefix: | so_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Increase Estimated In-service Capital Cost + References No definition available. + Details
Name: | so_EstimatedInServiceCapitalCost
Namespace Prefix: | so_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Increase (Decrease) In Tariff + References No definition available. + Details
Name: | so_IncreaseDecreaseInTariff
Namespace Prefix: | so_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Proceeds from Recovery of Financing Costs + References No definition available. + Details
Name: | so_ProceedsfromRecoveryofFinancingCosts
Namespace Prefix: | so_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Public Utilities, Return on Equity, Potential Decrease Each Month, Percentage + References No definition available. + Details
Name: | so_PublicUtilitiesReturnonEquityPotentialDecreaseEachMonthPercentage
Namespace Prefix: | so_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Retail Rate Of Return On Common Equity + References No definition available. + Details
Name: | so_RetailRateOfReturnOnCommonEquity
Namespace Prefix: | so_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Return On Equity Reduction, Negative Impact On Earnings + References No definition available. + Details
Name: | so_ReturnOnEquityReductionNegativeImpactOnEarnings
Namespace Prefix: | so_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 460 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (b)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482425/460-10-50-4 + Details
Name: | us-gaap_GuaranteeObligationsMaximumExposure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The net amount of all regulatory assets less all regulatory liabilities as of the end of the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 980 -SubTopic 340 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481878/980-340-50-1 + Details
Name: | us-gaap_NetRegulatoryAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Percentage of public utility's approved return on equity. + References No definition available. + Details
Name: | us-gaap_PublicUtilitiesApprovedReturnOnEquityPercentage
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
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 No definition available. + Details
Name: | us-gaap_PublicUtilitiesGeneralDisclosuresLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_RegulatoryAssetAxis=us-gaap_DeferredIncomeTaxChargesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_PublicUtilityAxis=so_PlantVogtleUnits3And4Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RegulatoryAssetAxis=so_DeferredIncomeTaxChargeDebtComponentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RegulatoryAssetAxis=so_DeferredIncomeTaxChargeEquityComponentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | so_VogtleConstructionMonitoringReportNumberAxis=so_TwentyFifthVogtleConstructionMonitoringReportMember
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: |