XML 165 R112.htm IDEA: XBRL DOCUMENT
v3.25.0.1

REGULATORY MATTERS - APC Rate CNP (Details) - Alabama Power - USD ($) $ in Millions | 1 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2022 | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Schedule of Regulatory Assets and Liabilities [Line Items] |  |  |  |
Under recovered certified power purchase agreements |  | $ 84 | $ 103 |
Retail revenue requirement for environmental compliance |  | 50 | $ 23 | $ 255
Retail revenue requirement for environmental compliance, as a percentage |  |  | (0.30%) | 3.70%
Over (under) recovered environmental clause |  | (35) | $ (33) |
Public utilities, approved rate increase (decrease), amount | $ 318 |  |  |
Approved rate increase, percent | 4.60% |  |  |
Other regulatory assets, current |  |  |  |
Schedule of Regulatory Assets and Liabilities [Line Items] |  |  |  |
Under recovered certified power purchase agreements |  | 17 | 18 |
Over (under) recovered environmental clause |  |  | (8) |
Other regulatory assets, deferred |  |  |  |
Schedule of Regulatory Assets and Liabilities [Line Items] |  |  |  |
Under recovered certified power purchase agreements |  | $ 67 | 85 |
Over (under) recovered environmental clause |  |  | $ (25) |

X
- Definition Environmental Compliance, Unrecovered Retail Revenue + References No definition available. + Details
Name: | so_EnvironmentalComplianceUnrecoveredRetailRevenue
Namespace Prefix: | so_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Environmental Compliance, Unrecovered Retail Revenue, Percentage + References No definition available. + Details
Name: | so_EnvironmentalComplianceUnrecoveredRetailRevenuePercentage
Namespace Prefix: | so_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Over (Under) Recovered Environmental Clause + References No definition available. + Details
Name: | so_OverUnderRecoveredEnvironmentalClause
Namespace Prefix: | so_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Schedule of Regulatory Assets and Liabilities. + References No definition available. + Details
Name: | so_ScheduleOfRegulatoryAssetsAndLiabilitiesLineItems
Namespace Prefix: | so_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Under Recovered Certified Power Purchase Agreements + References No definition available. + Details
Name: | so_UnderRecoveredCertifiedPowerPurchaseAgreements
Namespace Prefix: | so_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of public utility's approved rate increase (decrease) by regulatory agency. + References No definition available. + Details
Name: | us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Percentage of public utility's approved rate increase (decrease) by regulatory agency. + References No definition available. + Details
Name: | us-gaap_PublicUtilitiesApprovedRateIncreaseDecreasePercentage
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

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

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=so_OtherRegulatoryAssetsCurrentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=so_OtherRegulatoryAssetsDeferredMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |