XML 164 R111.htm IDEA: XBRL DOCUMENT
v3.25.0.1

REGULATORY MATTERS - APC Rate CNP New Plant (Details) - Alabama Power $ in Millions | 1 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | ---
Jun. 30, 2023 USD ($) | Dec. 31, 2020 MW | Dec. 01, 2023 USD ($) | Oct. 03, 2022 USD ($)
Public Utilities, General Disclosures [Line Items] |  |  |  |
Increase to annual revenue requirement |  |  | $ 91 | $ 34
Increase to annual revenue requirement, percentage |  |  | 1.40% | 0.60%
Requested rate increase (decrease), amount | $ 78 |  |  |
Requested rate increase (decrease), percentage | 1.10% |  |  |
Plant Barry Unit 8 |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |
Approximate Nameplate Capacity (MW) | MW |  | 720 |  |

X
- Definition Approximate Nameplate Capacity + References No definition available. + Details
Name: | so_ApproximateNameplateCapacity
Namespace Prefix: | so_
Data Type: | dtr-types1:powerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Certificated New Plant, Revenue Requirement Increase + References No definition available. + Details
Name: | so_CertificatedNewPlantRevenueRequirementIncrease
Namespace Prefix: | so_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Certificated New Plant, Revenue Requirement Increase, Percentage + References No definition available. + Details
Name: | so_CertificatedNewPlantRevenueRequirementIncreasePercentage
Namespace Prefix: | so_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | instant

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

X
- Definition Percentage of public utility's requested rate increase (decrease) with regulatory agency. + References No definition available. + Details
Name: | us-gaap_PublicUtilitiesRequestedRateIncreaseDecreasePercentage
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_PublicUtilityAxis=so_PlantBarryUnit8Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |