XML 158 R114.htm IDEA: XBRL DOCUMENT
v3.22.0.1

REGULATORY MATTERS - GPC Tariffs (Details) - Georgia Power $ in Millions | Dec. 31, 2019 USD ($)
--- | ---
Public Utilities, General Disclosures [Line Items] |
Rate increase 2020 | $ 342
Rate increase (decrease) 2021 | 111
Rate increase (decrease) 2022 | 157
Traditional base |
Public Utilities, General Disclosures [Line Items] |
Rate increase 2020 | 0
Rate increase (decrease) 2021 | 120
Rate increase (decrease) 2022 | 192
ECCR |
Public Utilities, General Disclosures [Line Items] |
Rate increase 2020 | 318
Rate increase (decrease) 2021 | 2
Rate increase (decrease) 2022 | (12)
DSM |
Public Utilities, General Disclosures [Line Items] |
Rate increase 2020 | 12
Rate increase (decrease) 2021 | (15)
Rate increase (decrease) 2022 | (25)
MFF |
Public Utilities, General Disclosures [Line Items] |
Rate increase 2020 | 12
Rate increase (decrease) 2021 | 4
Rate increase (decrease) 2022 | $ 2

X
- Definition Public Utilities, Requested Rate Increase (Decrease), Amount, Due In Next Fiscal Year + References No definition available. + Details
Name: | so_PublicUtilitiesRequestedRateIncreaseDecreaseAmountDueInNextFiscalYear
Namespace Prefix: | so_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Public Utilities, Requested Rate Increase (Decrease), Amount, Due In Second Year + References No definition available. + Details
Name: | so_PublicUtilitiesRequestedRateIncreaseDecreaseAmountDueInSecondYear
Namespace Prefix: | so_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Public Utilities, Requested Rate Increase (Decrease), Amount, Due In Third Year + References No definition available. + Details
Name: | so_PublicUtilitiesRequestedRateIncreaseDecreaseAmountDueInThirdYear
Namespace Prefix: | so_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
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
- Details
Name: | dei_LegalEntityAxis=so_GeorgiaPowerMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilitiesRegulatoryProceedingAxis=so_TraditionalBaseMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilitiesRegulatoryProceedingAxis=so_EnvironmentalComplianceCostRecoveryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilitiesRegulatoryProceedingAxis=so_DemandSideManagementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilitiesRegulatoryProceedingAxis=so_MunicipalFranchiseFeeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |