XML 221 R177.htm IDEA: XBRL DOCUMENT
v3.22.0.1

LEASES - Additional Information (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2021 | Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Lessee, Lease, Description [Line Items] |  |  |  |
Operating lease obligations | $ 1,754 | $ 1,754 | $ 1,852 |
Transfer of construction work in progress to lease receivables |  | $ 210 |  |
Communication towers |  |  |  |
Lessee, Lease, Description [Line Items] |  |  |  |
Lessee, renewal period |  | 15 years |  |
Maximum | Real estate |  |  |  |
Lessee, Lease, Description [Line Items] |  |  |  |
Remaining terms |  | 24 years |  |
Maximum | Land |  |  |  |
Lessee, Lease, Description [Line Items] |  |  |  |
Lessee, lease term |  | 45 years |  |
Maximum | Communication towers |  |  |  |
Lessee, Lease, Description [Line Items] |  |  |  |
Lessee, lease term |  | 15 years |  |
Maximum | Fuel cells |  |  |  |
Lessee, Lease, Description [Line Items] |  |  |  |
Lessor, lease term, operating lease | 12 years | 12 years |  |
Alabama Power |  |  |  |
Lessee, Lease, Description [Line Items] |  |  |  |
Operating lease obligations | $ 121 | $ 121 | 170 |
Alabama Power | Maximum | Electric generating units |  |  |  |
Lessee, Lease, Description [Line Items] |  |  |  |
Operating lease remaining lease term | 17 years | 17 years |  |
Alabama Power | Minimum | Electric generating units |  |  |  |
Lessee, Lease, Description [Line Items] |  |  |  |
Operating lease remaining lease term | 1 year | 1 year |  |
Georgia Power |  |  |  |
Lessee, Lease, Description [Line Items] |  |  |  |
Operating lease obligations | $ 1,155 | $ 1,155 | 1,307 |
Variable lease, payment |  | 41 | 39 | $ 42
Georgia Power | Purchased power, affiliates |  |  |  |
Lessee, Lease, Description [Line Items] |  |  |  |
Variable lease, payment |  | 20 | 20 | 20
Mississippi Power |  |  |  |
Lessee, Lease, Description [Line Items] |  |  |  |
Operating lease obligations | 10 | 10 | 9 |
Transfer of construction work in progress to lease receivables |  | 39 | 26 |
Sales-type lease, lease receivable | $ 39 | $ 39 | 26 |
Mississippi Power | Maximum | Electric generating units |  |  |  |
Lessee, Lease, Description [Line Items] |  |  |  |
Lessor, sales-type lease, term of contract | 17 years | 17 years |  |
Southern Power |  |  |  |
Lessee, Lease, Description [Line Items] |  |  |  |
Operating lease obligations | $ 525 | $ 525 | 451 |
Lessor, sales-type lease, term of contract | 20 years | 20 years |  |
Sales-type lease, lease receivable | $ 210 | $ 210 |  |
Loss on sales-type leases | 40 | 40 | 0 | $ 0
Net investment in sales-type lease, current portion | 12 | 12 |  |
Net investment in sales-type lease, long-term portion | $ 161 | $ 161 | 0 |
Southern Power | Maximum | Electric generating units |  |  |  |
Lessee, Lease, Description [Line Items] |  |  |  |
Lessor, lease term, operating lease | 25 years | 25 years |  |
Lessor, sales-type lease, term of contract | 19 years | 19 years |  |
Southern Company Gas |  |  |  |
Lessee, Lease, Description [Line Items] |  |  |  |
Operating lease obligations | $ 70 | $ 70 | 82 |
Southern Company Gas | Maximum |  |  |  |
Lessee, Lease, Description [Line Items] |  |  |  |
Lessor, remaining term |  | 21 years |  |
Affiliate | Georgia Power | Electric generating units |  |  |  |
Lessee, Lease, Description [Line Items] |  |  |  |
Operating lease obligations | $ 521 | $ 521 | $ 575 |
Traditional Electric Operating Companies | Maximum | Outdoor lighting |  |  |  |
Lessee, Lease, Description [Line Items] |  |  |  |
Lessor, lease term, operating lease | 7 years | 7 years |  |

X
- Definition Lease, Weighted Average Remaining Lease Term + References No definition available. + Details
Name: | so_LeaseWeightedAverageRemainingLeaseTerm
Namespace Prefix: | so_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Lessee, Lease, Renewal Term + References No definition available. + Details
Name: | so_LesseeLeaseRenewalTerm
Namespace Prefix: | so_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Lessee, Lease, Term Of Contract + References No definition available. + Details
Name: | so_LesseeLeaseTermOfContract
Namespace Prefix: | so_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Lessor, Operating Lease, Remaining Lease Term + References No definition available. + Details
Name: | so_LessorOperatingLeaseRemainingLeaseTerm
Namespace Prefix: | so_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Transfer Of Construction Work In Progress To Lease Receivables + References No definition available. + Details
Name: | so_TransferOfConstructionWorkInProgressToLeaseReceivables
Namespace Prefix: | so_
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 No definition available. + Details
Name: | us-gaap_LesseeLeaseDescriptionLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Remaining lease term of operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=123408670&loc=SL77918673-209980 + Details
Name: | us-gaap_LesseeOperatingLeaseRemainingLeaseTerm
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | instant

X
- Definition Term of lessor's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 30 -Section 50 -Paragraph 3 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=124258985&loc=SL77919359-209981 + Details
Name: | us-gaap_LessorOperatingLeaseTermOfContract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | instant

X
- Definition Term of lessor's sales-type lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 30 -Section 50 -Paragraph 3 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=124258985&loc=SL77919359-209981 + Details
Name: | us-gaap_LessorSalesTypeLeaseTermOfContract1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | instant

X
- Definition Present value of lessee's discounted obligation for lease payments from operating lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123391704&loc=SL77918627-209977 + Details
Name: | us-gaap_OperatingLeaseLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Present value of lease payments not yet received by lessor and amount expected to be derived from underlying asset, following end of lease term guaranteed by lessee or other third party unrelated to lessor, from sales-type lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 30 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=124258985&loc=SL77919379-209981 + Details
Name: | us-gaap_SalesTypeLeaseLeaseReceivable
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount, after allowance for credit loss, of net investment in sales-type lease, classified as current. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=123420820&loc=SL77919306-209978 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=123420820&loc=SL77919308-209978 + Details
Name: | us-gaap_SalesTypeLeaseNetInvestmentInLeaseAfterAllowanceForCreditLossCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount, after allowance for credit loss, of net investment in sales-type lease, classified as noncurrent. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=123420820&loc=SL77919308-209978 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=123420820&loc=SL77919306-209978 + Details
Name: | us-gaap_SalesTypeLeaseNetInvestmentInLeaseAfterAllowanceForCreditLossNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of profit (loss) recognized at commencement from sales-type lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 30 -Section 50 -Paragraph 5 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=124258985&loc=SL77919372-209981 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 270 -SubTopic 10 -Section 50 -Paragraph 6A -URI http://asc.fasb.org/extlink&oid=124502072&loc=SL77927221-108306 + Details
Name: | us-gaap_SalesTypeLeaseSellingProfitLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of cash outflow for variable lease payment excluded from lease liability. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 5 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=123391704&loc=SL77918643-209977 + Details
Name: | us-gaap_VariableLeasePayment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=so_CommunicationTowersMember
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: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_BuildingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_LandMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=so_FuelCellsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=so_ElectricGeneratingUnitsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
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: | srt_ProductOrServiceAxis=so_ElectricityPurchasedAffiliatesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

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

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=srt_AffiliatedEntityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=so_TraditionalElectricOperatingCompaniesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=so_OutdoorLightingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |