0000092122-22-000003.txt : 20220217 0000092122-22-000003.hdr.sgml : 20220217 20220216174430 ACCESSION NUMBER: 0000092122-22-000003 CONFORMED SUBMISSION TYPE: 10-K PUBLIC DOCUMENT COUNT: 290 CONFORMED PERIOD OF REPORT: 20211231 FILED AS OF DATE: 20220217 DATE AS OF CHANGE: 20220216 FILER: COMPANY DATA: COMPANY CONFORMED NAME: SOUTHERN CO CENTRAL INDEX KEY: 0000092122 STANDARD INDUSTRIAL CLASSIFICATION: ELECTRIC SERVICES [4911] IRS NUMBER: 580690070 STATE OF INCORPORATION: DE FISCAL YEAR END: 1231 FILING VALUES: FORM TYPE: 10-K SEC ACT: 1934 Act SEC FILE NUMBER: 001-03526 FILM NUMBER: 22644867 BUSINESS ADDRESS: STREET 1: 30 IVAN ALLEN JR. BLVD., N.W. CITY: ATLANTA STATE: GA ZIP: 30308 BUSINESS PHONE: 4045065000 MAIL ADDRESS: STREET 1: 30 IVAN ALLEN JR. BLVD., N.W. CITY: ATLANTA STATE: GA ZIP: 30308 FILER: COMPANY DATA: COMPANY CONFORMED NAME: GEORGIA POWER CO CENTRAL INDEX KEY: 0000041091 STANDARD INDUSTRIAL CLASSIFICATION: ELECTRIC SERVICES [4911] IRS NUMBER: 580257110 STATE OF INCORPORATION: GA FISCAL YEAR END: 1231 FILING VALUES: FORM TYPE: 10-K SEC ACT: 1934 Act SEC FILE NUMBER: 001-06468 FILM NUMBER: 22644871 BUSINESS ADDRESS: STREET 1: 241 RALPH MCGILL BOULEVARD CITY: ATLANTA STATE: GA ZIP: 30308 BUSINESS PHONE: 4045066526 MAIL ADDRESS: STREET 1: 241 RALPH MCGILL BOULEVARD CITY: ATLANTA STATE: GA ZIP: 30308 FILER: COMPANY DATA: COMPANY CONFORMED NAME: SOUTHERN POWER CO CENTRAL INDEX KEY: 0001160661 STANDARD INDUSTRIAL CLASSIFICATION: ELECTRIC SERVICES [4911] IRS NUMBER: 582598670 FILING VALUES: FORM TYPE: 10-K SEC ACT: 1934 Act SEC FILE NUMBER: 001-37803 FILM NUMBER: 22644869 BUSINESS ADDRESS: STREET 1: 30 IVAN ALLEN JR. BLVD CITY: ATLANTA STATE: GA ZIP: 30308 BUSINESS PHONE: 4045065000 MAIL ADDRESS: STREET 1: 30 IVAN ALLEN JR. BLVD CITY: ATLANTA STATE: GA ZIP: 30308 FILER: COMPANY DATA: COMPANY CONFORMED NAME: SOUTHERN Co GAS CENTRAL INDEX KEY: 0001004155 STANDARD INDUSTRIAL CLASSIFICATION: NATURAL GAS DISTRIBUTION [4924] IRS NUMBER: 582210952 STATE OF INCORPORATION: GA FISCAL YEAR END: 1231 FILING VALUES: FORM TYPE: 10-K SEC ACT: 1934 Act SEC FILE NUMBER: 001-14174 FILM NUMBER: 22644868 BUSINESS ADDRESS: STREET 1: 30 IVAN ALLEN JR. BLVD CITY: ATLANTA STATE: GA ZIP: 30308 BUSINESS PHONE: 4045065000 MAIL ADDRESS: STREET 1: 30 IVAN ALLEN JR. BLVD CITY: ATLANTA STATE: GA ZIP: 30308 FORMER COMPANY: FORMER CONFORMED NAME: AGL RESOURCES INC DATE OF NAME CHANGE: 19951129 FILER: COMPANY DATA: COMPANY CONFORMED NAME: ALABAMA POWER CO CENTRAL INDEX KEY: 0000003153 STANDARD INDUSTRIAL CLASSIFICATION: ELECTRIC SERVICES [4911] IRS NUMBER: 630004250 STATE OF INCORPORATION: AL FISCAL YEAR END: 1231 FILING VALUES: FORM TYPE: 10-K SEC ACT: 1934 Act SEC FILE NUMBER: 001-03164 FILM NUMBER: 22644872 BUSINESS ADDRESS: STREET 1: 600 N 18TH ST STREET 2: P O BOX 2641 CITY: BIRMINGHAM STATE: AL ZIP: 35291 BUSINESS PHONE: 2052571000 MAIL ADDRESS: STREET 1: 600 N 18TH ST CITY: BIRMINGHAM STATE: AL ZIP: 35291 FILER: COMPANY DATA: COMPANY CONFORMED NAME: MISSISSIPPI POWER CO CENTRAL INDEX KEY: 0000066904 STANDARD INDUSTRIAL CLASSIFICATION: ELECTRIC SERVICES [4911] IRS NUMBER: 640205820 STATE OF INCORPORATION: MS FISCAL YEAR END: 1231 FILING VALUES: FORM TYPE: 10-K SEC ACT: 1934 Act SEC FILE NUMBER: 001-11229 FILM NUMBER: 22644870 BUSINESS ADDRESS: STREET 1: 2992 WEST BEACH CITY: GULFPORT STATE: MS ZIP: 39501 BUSINESS PHONE: 2288641211 MAIL ADDRESS: STREET 1: 2992 WEST BEACH CITY: GULFPORT STATE: MS ZIP: 39501 10-K 1 so-20211231.htm 10-K

000009212200000031530000041091000006690400011606610001004155FALSE2021FYnononoP2Ythree years, six months0.333333.3366.67P3M1828411111111111111111111P5Y.000025.000025P1Yhttp://fasb.org/us-gaap/2021-01-31#OtherAssetsNoncurrenthttp://fasb.org/us-gaap/2021-01-31#OtherLiabilitiesCurrenthttp://fasb.org/us-gaap/2021-01-31#OtherLiabilitiesCurrenthttp://fasb.org/us-gaap/2021-01-31#OtherLiabilitiesCurrenthttp://fasb.org/us-gaap/2021-01-31#OtherLiabilitiesCurrenthttp://fasb.org/us-gaap/2021-01-31#OtherLiabilitiesNoncurrenthttp://southerncompany.com/20211231#PlantInServiceNetOfDepreciationhttp://southerncompany.com/20211231#PlantInServiceNetOfDepreciationhttp://southerncompany.com/20211231#PlantInServiceNetOfDepreciationhttp://southerncompany.com/20211231#PlantInServiceNetOfDepreciationhttp://fasb.org/us-gaap/2021-01-31#OtherLiabilitiesCurrenthttp://fasb.org/us-gaap/2021-01-31#OtherLiabilitiesCurrenthttp://fasb.org/us-gaap/2021-01-31#OtherLiabilitiesCurrenthttp://fasb.org/us-gaap/2021-01-31#OtherLiabilitiesCurrenthttp://fasb.org/us-gaap/2021-01-31#LongTermDebtAndCapitalLeaseObligationshttp://fasb.org/us-gaap/2021-01-31#LongTermDebtAndCapitalLeaseObligationshttp://fasb.org/us-gaap/2021-01-31#LongTermDebtAndCapitalLeaseObligationshttp://fasb.org/us-gaap/2021-01-31#LongTermDebtAndCapitalLeaseObligationshttp://fasb.org/us-gaap/2021-01-31#OtherAssetsNoncurrenthttp://fasb.org/us-gaap/2021-01-31#OtherLiabilitiesCurrenthttp://fasb.org/us-gaap/2021-01-31#OtherLiabilitiesCurrenthttp://fasb.org/us-gaap/2021-01-31#OtherLiabilitiesCurrenthttp://fasb.org/us-gaap/2021-01-31#OtherLiabilitiesCurrenthttp://fasb.org/us-gaap/2021-01-31#OtherLiabilitiesNoncurrenthttp://southerncompany.com/20211231#PlantInServiceNetOfDepreciationhttp://southerncompany.com/20211231#PlantInServiceNetOfDepreciationhttp://southerncompany.com/20211231#PlantInServiceNetOfDepreciationhttp://southerncompany.com/20211231#PlantInServiceNetOfDepreciationhttp://fasb.org/us-gaap/2021-01-31#OtherLiabilitiesCurrenthttp://fasb.org/us-gaap/2021-01-31#OtherLiabilitiesCurrenthttp://fasb.org/us-gaap/2021-01-31#OtherLiabilitiesCurrenthttp://fasb.org/us-gaap/2021-01-31#OtherLiabilitiesCurrenthttp://fasb.org/us-gaap/2021-01-31#LongTermDebtAndCapitalLeaseObligationshttp://fasb.org/us-gaap/2021-01-31#LongTermDebtAndCapitalLeaseObligationshttp://fasb.org/us-gaap/2021-01-31#LongTermDebtAndCapitalLeaseObligationshttp://fasb.org/us-gaap/2021-01-31#LongTermDebtAndCapitalLeaseObligationsP3YP1YP2Y00000921222021-01-012021-12-310000092122so:AlabamaPowerMember2021-01-012021-12-310000092122so:GeorgiaPowerMember2021-01-012021-12-310000092122so:MississippiPowerMember2021-01-012021-12-310000092122so:SouthernPowerMember2021-01-012021-12-310000092122so:SouthernCompanyGasMember2021-01-012021-12-310000092122us-gaap:CommonStockMember2021-01-012021-12-310000092122so:Series2017B5.25JuniorSubordinatedNotesDue2077Member2021-01-012021-12-310000092122so:TwoThousandNineteenSeriesACorporateUnitsMember2021-01-012021-12-310000092122so:Series2020A4.95JuniorSubordinatedNotesDue2080Member2021-01-012021-12-310000092122so:Series2020C420JuniorSubordinatedNotesDue2060Member2021-01-012021-12-310000092122so:Series2021B1875FixedToFixedResetRateJuniorSubordinatedNotesDue2081Member2021-01-012021-12-310000092122so:AlabamaPowerMemberso:A5.00SeriesClassAPreferredStockMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:Series2017A5.00JuniorSubordinatedNotesDue2077Member2021-01-012021-12-310000092122so:Series2016A1.000SeniorNotesDue2022Memberso:SouthernPowerMember2021-01-012021-12-310000092122so:Series2016B1.850SeniorNotesDue2026Memberso:SouthernPowerMember2021-01-012021-12-310000092122so:PreferredStockCumulative100ParValue4.20SeriesMemberso:AlabamaPowerMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:PreferredStockCumulative100ParValue4.52SeriesMember2021-01-012021-12-310000092122so:PreferredStockCumulative100ParValue4.60SeriesMemberso:AlabamaPowerMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:PreferredStockCumulative100ParValue4.64SeriesMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:PreferredStockCumulative100ParValue4.72SeriesMember2021-01-012021-12-310000092122so:PreferredStockCumulative100ParValue4.92SeriesMemberso:AlabamaPowerMember2021-01-012021-12-3100000921222021-06-30iso4217:USD00000921222022-01-31xbrli:shares0000092122so:AlabamaPowerMember2022-01-310000092122so:GeorgiaPowerMember2022-01-310000092122so:MississippiPowerMember2022-01-310000092122so:SouthernPowerMember2022-01-310000092122so:SouthernCompanyGasMember2022-01-310000092122us-gaap:RetailMember2021-01-012021-12-310000092122us-gaap:RetailMember2020-01-012020-12-310000092122us-gaap:RetailMember2019-01-012019-12-310000092122so:WholesaleNonAffiliatesMember2021-01-012021-12-310000092122so:WholesaleNonAffiliatesMember2020-01-012020-12-310000092122so:WholesaleNonAffiliatesMember2019-01-012019-12-310000092122so:OtherElectricRevenueMember2021-01-012021-12-310000092122so:OtherElectricRevenueMember2020-01-012020-12-310000092122so:OtherElectricRevenueMember2019-01-012019-12-310000092122us-gaap:NaturalGasUsRegulatedMember2021-01-012021-12-310000092122us-gaap:NaturalGasUsRegulatedMember2020-01-012020-12-310000092122us-gaap:NaturalGasUsRegulatedMember2019-01-012019-12-310000092122us-gaap:ProductAndServiceOtherMember2021-01-012021-12-310000092122us-gaap:ProductAndServiceOtherMember2020-01-012020-12-310000092122us-gaap:ProductAndServiceOtherMember2019-01-012019-12-3100000921222020-01-012020-12-3100000921222019-01-012019-12-310000092122srt:FuelMember2021-01-012021-12-310000092122srt:FuelMember2020-01-012020-12-310000092122srt:FuelMember2019-01-012019-12-310000092122us-gaap:ElectricityPurchasedMember2021-01-012021-12-310000092122us-gaap:ElectricityPurchasedMember2020-01-012020-12-310000092122us-gaap:ElectricityPurchasedMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:PlantVogtleUnits3And4Memberso:TraditionalOperatingCompaniesMember2020-01-012020-12-31iso4217:USDxbrli:shares00000921222020-12-3100000921222019-12-3100000921222018-12-3100000921222021-12-310000092122so:RedeemablePreferredStockTypeOneMember2020-12-310000092122so:RedeemablePreferredStockTypeOneMember2021-12-310000092122so:RedeemablePreferredStockTypeOneMembersrt:MinimumMember2020-01-012020-12-31xbrli:pure0000092122so:RedeemablePreferredStockTypeOneMembersrt:MinimumMember2021-01-012021-12-310000092122so:RedeemablePreferredStockTypeOneMembersrt:MaximumMember2020-01-012020-12-310000092122so:RedeemablePreferredStockTypeOneMembersrt:MaximumMember2021-01-012021-12-310000092122so:RedeemablePreferredStockTypeTwoMember2021-12-310000092122so:RedeemablePreferredStockTypeTwoMember2020-12-310000092122so:RedeemablePreferredStockTypeTwoMember2020-01-012020-12-310000092122so:RedeemablePreferredStockTypeTwoMember2021-01-012021-12-310000092122us-gaap:RedeemablePreferredStockMember2020-12-310000092122us-gaap:RedeemablePreferredStockMember2021-12-310000092122us-gaap:CommonStockMember2018-12-310000092122us-gaap:TreasuryStockMember2018-12-310000092122us-gaap:AdditionalPaidInCapitalMember2018-12-310000092122us-gaap:RetainedEarningsMember2018-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMember2018-12-310000092122us-gaap:NoncontrollingInterestMember2018-12-310000092122us-gaap:RetainedEarningsMember2019-01-012019-12-310000092122us-gaap:NoncontrollingInterestMember2019-01-012019-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMember2019-01-012019-12-310000092122us-gaap:AdditionalPaidInCapitalMember2019-01-012019-12-310000092122us-gaap:CommonStockMember2019-01-012019-12-310000092122us-gaap:TreasuryStockMember2019-01-012019-12-310000092122us-gaap:CommonStockMember2019-12-310000092122us-gaap:TreasuryStockMember2019-12-310000092122us-gaap:AdditionalPaidInCapitalMember2019-12-310000092122us-gaap:RetainedEarningsMember2019-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMember2019-12-310000092122us-gaap:NoncontrollingInterestMember2019-12-310000092122us-gaap:RetainedEarningsMember2020-01-012020-12-310000092122us-gaap:NoncontrollingInterestMember2020-01-012020-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMember2020-01-012020-12-310000092122us-gaap:CommonStockMember2020-01-012020-12-310000092122us-gaap:AdditionalPaidInCapitalMember2020-01-012020-12-310000092122us-gaap:TreasuryStockMember2020-01-012020-12-310000092122us-gaap:CommonStockMember2020-12-310000092122us-gaap:TreasuryStockMember2020-12-310000092122us-gaap:AdditionalPaidInCapitalMember2020-12-310000092122us-gaap:RetainedEarningsMember2020-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMember2020-12-310000092122us-gaap:NoncontrollingInterestMember2020-12-310000092122us-gaap:RetainedEarningsMember2021-01-012021-12-310000092122us-gaap:NoncontrollingInterestMember2021-01-012021-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMember2021-01-012021-12-310000092122us-gaap:CommonStockMember2021-01-012021-12-310000092122us-gaap:AdditionalPaidInCapitalMember2021-01-012021-12-310000092122us-gaap:TreasuryStockMember2021-01-012021-12-310000092122us-gaap:CommonStockMember2021-12-310000092122us-gaap:TreasuryStockMember2021-12-310000092122us-gaap:AdditionalPaidInCapitalMember2021-12-310000092122us-gaap:RetainedEarningsMember2021-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMember2021-12-310000092122us-gaap:NoncontrollingInterestMember2021-12-310000092122so:AlabamaPowerMemberus-gaap:RetailMember2021-01-012021-12-310000092122so:AlabamaPowerMemberus-gaap:RetailMember2020-01-012020-12-310000092122so:AlabamaPowerMemberus-gaap:RetailMember2019-01-012019-12-310000092122so:WholesaleNonAffiliatesMemberso:AlabamaPowerMember2021-01-012021-12-310000092122so:WholesaleNonAffiliatesMemberso:AlabamaPowerMember2020-01-012020-12-310000092122so:WholesaleNonAffiliatesMemberso:AlabamaPowerMember2019-01-012019-12-310000092122so:AlabamaPowerMemberso:WholesaleAffiliatesMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:WholesaleAffiliatesMember2020-01-012020-12-310000092122so:AlabamaPowerMemberso:WholesaleAffiliatesMember2019-01-012019-12-310000092122so:AlabamaPowerMemberus-gaap:ProductAndServiceOtherMember2021-01-012021-12-310000092122so:AlabamaPowerMemberus-gaap:ProductAndServiceOtherMember2020-01-012020-12-310000092122so:AlabamaPowerMemberus-gaap:ProductAndServiceOtherMember2019-01-012019-12-310000092122so:AlabamaPowerMember2020-01-012020-12-310000092122so:AlabamaPowerMember2019-01-012019-12-310000092122so:AlabamaPowerMembersrt:FuelMember2021-01-012021-12-310000092122so:AlabamaPowerMembersrt:FuelMember2020-01-012020-12-310000092122so:AlabamaPowerMembersrt:FuelMember2019-01-012019-12-310000092122so:AlabamaPowerMemberus-gaap:ElectricityPurchasedMember2021-01-012021-12-310000092122so:AlabamaPowerMemberus-gaap:ElectricityPurchasedMember2020-01-012020-12-310000092122so:AlabamaPowerMemberus-gaap:ElectricityPurchasedMember2019-01-012019-12-310000092122so:AlabamaPowerMemberso:ElectricityPurchasedAffiliatesMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:ElectricityPurchasedAffiliatesMember2020-01-012020-12-310000092122so:AlabamaPowerMemberso:ElectricityPurchasedAffiliatesMember2019-01-012019-12-310000092122so:AlabamaPowerMember2020-12-310000092122so:AlabamaPowerMember2019-12-310000092122so:AlabamaPowerMember2018-12-310000092122so:AlabamaPowerMember2021-12-310000092122so:RedeemablePreferredStockTypeOneMemberso:AlabamaPowerMember2020-12-310000092122so:RedeemablePreferredStockTypeOneMemberso:AlabamaPowerMember2021-12-310000092122so:RedeemablePreferredStockTypeOneMemberso:AlabamaPowerMembersrt:MinimumMember2020-01-012020-12-310000092122so:RedeemablePreferredStockTypeOneMemberso:AlabamaPowerMembersrt:MinimumMember2021-01-012021-12-310000092122so:RedeemablePreferredStockTypeOneMemberso:AlabamaPowerMembersrt:MaximumMember2020-01-012020-12-310000092122so:RedeemablePreferredStockTypeOneMemberso:AlabamaPowerMembersrt:MaximumMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:RedeemablePreferredStockTypeTwoMember2021-12-310000092122so:AlabamaPowerMemberso:RedeemablePreferredStockTypeTwoMember2020-12-310000092122so:AlabamaPowerMemberso:RedeemablePreferredStockTypeTwoMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:RedeemablePreferredStockTypeTwoMember2020-01-012020-12-310000092122so:RedeemablePreferredStockTypeThreeMemberso:AlabamaPowerMember2021-12-310000092122so:RedeemablePreferredStockTypeThreeMemberso:AlabamaPowerMember2020-12-310000092122so:AlabamaPowerMemberus-gaap:RedeemablePreferredStockMember2020-12-310000092122so:AlabamaPowerMemberus-gaap:RedeemablePreferredStockMember2021-12-310000092122so:AlabamaPowerMemberus-gaap:CommonStockMember2018-12-310000092122us-gaap:AdditionalPaidInCapitalMemberso:AlabamaPowerMember2018-12-310000092122us-gaap:RetainedEarningsMemberso:AlabamaPowerMember2018-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:AlabamaPowerMember2018-12-310000092122us-gaap:RetainedEarningsMemberso:AlabamaPowerMember2019-01-012019-12-310000092122us-gaap:AdditionalPaidInCapitalMemberso:AlabamaPowerMember2019-01-012019-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:AlabamaPowerMember2019-01-012019-12-310000092122so:AlabamaPowerMemberus-gaap:CommonStockMember2019-12-310000092122us-gaap:AdditionalPaidInCapitalMemberso:AlabamaPowerMember2019-12-310000092122us-gaap:RetainedEarningsMemberso:AlabamaPowerMember2019-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:AlabamaPowerMember2019-12-310000092122us-gaap:RetainedEarningsMemberso:AlabamaPowerMember2020-01-012020-12-310000092122us-gaap:AdditionalPaidInCapitalMemberso:AlabamaPowerMember2020-01-012020-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:AlabamaPowerMember2020-01-012020-12-310000092122so:AlabamaPowerMemberus-gaap:CommonStockMember2020-12-310000092122us-gaap:AdditionalPaidInCapitalMemberso:AlabamaPowerMember2020-12-310000092122us-gaap:RetainedEarningsMemberso:AlabamaPowerMember2020-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:AlabamaPowerMember2020-12-310000092122us-gaap:RetainedEarningsMemberso:AlabamaPowerMember2021-01-012021-12-310000092122us-gaap:AdditionalPaidInCapitalMemberso:AlabamaPowerMember2021-01-012021-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:AlabamaPowerMember2021-01-012021-12-310000092122so:AlabamaPowerMemberus-gaap:CommonStockMember2021-12-310000092122us-gaap:AdditionalPaidInCapitalMemberso:AlabamaPowerMember2021-12-310000092122us-gaap:RetainedEarningsMemberso:AlabamaPowerMember2021-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:AlabamaPowerMember2021-12-310000092122so:GeorgiaPowerMemberus-gaap:RetailMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberus-gaap:RetailMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberus-gaap:RetailMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:WholesaleNonAffiliatesMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:WholesaleNonAffiliatesMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:WholesaleNonAffiliatesMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberus-gaap:ProductAndServiceOtherMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberus-gaap:ProductAndServiceOtherMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberus-gaap:ProductAndServiceOtherMember2019-01-012019-12-310000092122so:GeorgiaPowerMember2020-01-012020-12-310000092122so:GeorgiaPowerMember2019-01-012019-12-310000092122so:GeorgiaPowerMembersrt:FuelMember2021-01-012021-12-310000092122so:GeorgiaPowerMembersrt:FuelMember2020-01-012020-12-310000092122so:GeorgiaPowerMembersrt:FuelMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberus-gaap:ElectricityPurchasedMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberus-gaap:ElectricityPurchasedMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberus-gaap:ElectricityPurchasedMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:ElectricityPurchasedAffiliatesMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:ElectricityPurchasedAffiliatesMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:ElectricityPurchasedAffiliatesMember2019-01-012019-12-310000092122so:GeorgiaPowerMember2020-12-310000092122so:GeorgiaPowerMember2019-12-310000092122so:GeorgiaPowerMember2018-12-310000092122so:GeorgiaPowerMember2021-12-310000092122so:GeorgiaPowerMemberus-gaap:CommonStockMember2018-12-310000092122so:GeorgiaPowerMemberus-gaap:AdditionalPaidInCapitalMember2018-12-310000092122us-gaap:RetainedEarningsMemberso:GeorgiaPowerMember2018-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:GeorgiaPowerMember2018-12-310000092122us-gaap:RetainedEarningsMemberso:GeorgiaPowerMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberus-gaap:AdditionalPaidInCapitalMember2019-01-012019-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:GeorgiaPowerMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberus-gaap:CommonStockMember2019-12-310000092122so:GeorgiaPowerMemberus-gaap:AdditionalPaidInCapitalMember2019-12-310000092122us-gaap:RetainedEarningsMemberso:GeorgiaPowerMember2019-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:GeorgiaPowerMember2019-12-310000092122us-gaap:RetainedEarningsMemberso:GeorgiaPowerMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberus-gaap:AdditionalPaidInCapitalMember2020-01-012020-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:GeorgiaPowerMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberus-gaap:CommonStockMember2020-12-310000092122so:GeorgiaPowerMemberus-gaap:AdditionalPaidInCapitalMember2020-12-310000092122us-gaap:RetainedEarningsMemberso:GeorgiaPowerMember2020-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:GeorgiaPowerMember2020-12-310000092122us-gaap:RetainedEarningsMemberso:GeorgiaPowerMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberus-gaap:AdditionalPaidInCapitalMember2021-01-012021-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:GeorgiaPowerMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberus-gaap:CommonStockMember2021-12-310000092122so:GeorgiaPowerMemberus-gaap:AdditionalPaidInCapitalMember2021-12-310000092122us-gaap:RetainedEarningsMemberso:GeorgiaPowerMember2021-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:GeorgiaPowerMember2021-12-310000092122so:MississippiPowerMemberus-gaap:RetailMember2021-01-012021-12-310000092122so:MississippiPowerMemberus-gaap:RetailMember2020-01-012020-12-310000092122so:MississippiPowerMemberus-gaap:RetailMember2019-01-012019-12-310000092122so:WholesaleNonAffiliatesMemberso:MississippiPowerMember2021-01-012021-12-310000092122so:WholesaleNonAffiliatesMemberso:MississippiPowerMember2020-01-012020-12-310000092122so:WholesaleNonAffiliatesMemberso:MississippiPowerMember2019-01-012019-12-310000092122so:MississippiPowerMemberso:WholesaleAffiliatesMember2021-01-012021-12-310000092122so:MississippiPowerMemberso:WholesaleAffiliatesMember2020-01-012020-12-310000092122so:MississippiPowerMemberso:WholesaleAffiliatesMember2019-01-012019-12-310000092122so:MississippiPowerMemberus-gaap:ProductAndServiceOtherMember2021-01-012021-12-310000092122so:MississippiPowerMemberus-gaap:ProductAndServiceOtherMember2020-01-012020-12-310000092122so:MississippiPowerMemberus-gaap:ProductAndServiceOtherMember2019-01-012019-12-310000092122so:MississippiPowerMember2020-01-012020-12-310000092122so:MississippiPowerMember2019-01-012019-12-310000092122srt:FuelMemberso:MississippiPowerMember2021-01-012021-12-310000092122srt:FuelMemberso:MississippiPowerMember2020-01-012020-12-310000092122srt:FuelMemberso:MississippiPowerMember2019-01-012019-12-310000092122so:MississippiPowerMemberus-gaap:ElectricityPurchasedMember2021-01-012021-12-310000092122so:MississippiPowerMemberus-gaap:ElectricityPurchasedMember2020-01-012020-12-310000092122so:MississippiPowerMemberus-gaap:ElectricityPurchasedMember2019-01-012019-12-310000092122so:MississippiPowerMember2020-12-310000092122so:MississippiPowerMember2019-12-310000092122so:MississippiPowerMember2018-12-310000092122so:MississippiPowerMember2021-12-310000092122so:MississippiPowerMemberus-gaap:CommonStockMember2018-12-310000092122us-gaap:AdditionalPaidInCapitalMemberso:MississippiPowerMember2018-12-310000092122us-gaap:RetainedEarningsMemberso:MississippiPowerMember2018-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:MississippiPowerMember2018-12-310000092122us-gaap:RetainedEarningsMemberso:MississippiPowerMember2019-01-012019-12-310000092122us-gaap:AdditionalPaidInCapitalMemberso:MississippiPowerMember2019-01-012019-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:MississippiPowerMember2019-01-012019-12-310000092122so:MississippiPowerMemberus-gaap:CommonStockMember2019-12-310000092122us-gaap:AdditionalPaidInCapitalMemberso:MississippiPowerMember2019-12-310000092122us-gaap:RetainedEarningsMemberso:MississippiPowerMember2019-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:MississippiPowerMember2019-12-310000092122us-gaap:RetainedEarningsMemberso:MississippiPowerMember2020-01-012020-12-310000092122us-gaap:AdditionalPaidInCapitalMemberso:MississippiPowerMember2020-01-012020-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:MississippiPowerMember2020-01-012020-12-310000092122so:MississippiPowerMemberus-gaap:CommonStockMember2020-12-310000092122us-gaap:AdditionalPaidInCapitalMemberso:MississippiPowerMember2020-12-310000092122us-gaap:RetainedEarningsMemberso:MississippiPowerMember2020-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:MississippiPowerMember2020-12-310000092122us-gaap:RetainedEarningsMemberso:MississippiPowerMember2021-01-012021-12-310000092122us-gaap:AdditionalPaidInCapitalMemberso:MississippiPowerMember2021-01-012021-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:MississippiPowerMember2021-01-012021-12-310000092122so:MississippiPowerMemberus-gaap:CommonStockMember2021-12-310000092122us-gaap:AdditionalPaidInCapitalMemberso:MississippiPowerMember2021-12-310000092122us-gaap:RetainedEarningsMemberso:MississippiPowerMember2021-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:MississippiPowerMember2021-12-310000092122so:WholesaleNonAffiliatesMemberso:SouthernPowerMember2021-01-012021-12-310000092122so:WholesaleNonAffiliatesMemberso:SouthernPowerMember2020-01-012020-12-310000092122so:WholesaleNonAffiliatesMemberso:SouthernPowerMember2019-01-012019-12-310000092122so:TraditionalElectricOperatingCompaniesMemberso:SouthernPowerMemberso:WholesaleAffiliatesMember2021-01-012021-12-310000092122so:TraditionalElectricOperatingCompaniesMemberso:SouthernPowerMemberso:WholesaleAffiliatesMember2020-01-012020-12-310000092122so:TraditionalElectricOperatingCompaniesMemberso:SouthernPowerMemberso:WholesaleAffiliatesMember2019-01-012019-12-310000092122us-gaap:ProductAndServiceOtherMemberso:SouthernPowerMember2021-01-012021-12-310000092122us-gaap:ProductAndServiceOtherMemberso:SouthernPowerMember2020-01-012020-12-310000092122us-gaap:ProductAndServiceOtherMemberso:SouthernPowerMember2019-01-012019-12-310000092122so:SouthernPowerMember2020-01-012020-12-310000092122so:SouthernPowerMember2019-01-012019-12-310000092122srt:FuelMemberso:SouthernPowerMember2021-01-012021-12-310000092122srt:FuelMemberso:SouthernPowerMember2020-01-012020-12-310000092122srt:FuelMemberso:SouthernPowerMember2019-01-012019-12-310000092122us-gaap:ElectricityPurchasedMemberso:SouthernPowerMember2021-01-012021-12-310000092122us-gaap:ElectricityPurchasedMemberso:SouthernPowerMember2020-01-012020-12-310000092122us-gaap:ElectricityPurchasedMemberso:SouthernPowerMember2019-01-012019-12-310000092122so:SouthernPowerMember2020-12-310000092122so:SouthernPowerMember2019-12-310000092122so:SouthernPowerMember2018-12-310000092122so:SouthernPowerMember2021-12-310000092122us-gaap:AdditionalPaidInCapitalMemberso:SouthernPowerMember2018-12-310000092122us-gaap:RetainedEarningsMemberso:SouthernPowerMember2018-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:SouthernPowerMember2018-12-310000092122so:CommonStockholdersEquityNotIncludingNoncontrollingInterestMemberso:SouthernPowerMember2018-12-310000092122us-gaap:NoncontrollingInterestMemberso:SouthernPowerMember2018-12-310000092122us-gaap:RetainedEarningsMemberso:SouthernPowerMember2019-01-012019-12-310000092122so:CommonStockholdersEquityNotIncludingNoncontrollingInterestMemberso:SouthernPowerMember2019-01-012019-12-310000092122us-gaap:NoncontrollingInterestMemberso:SouthernPowerMember2019-01-012019-12-310000092122us-gaap:AdditionalPaidInCapitalMemberso:SouthernPowerMember2019-01-012019-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:SouthernPowerMember2019-01-012019-12-310000092122us-gaap:AdditionalPaidInCapitalMemberso:SouthernPowerMember2019-12-310000092122us-gaap:RetainedEarningsMemberso:SouthernPowerMember2019-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:SouthernPowerMember2019-12-310000092122so:CommonStockholdersEquityNotIncludingNoncontrollingInterestMemberso:SouthernPowerMember2019-12-310000092122us-gaap:NoncontrollingInterestMemberso:SouthernPowerMember2019-12-310000092122us-gaap:RetainedEarningsMemberso:SouthernPowerMember2020-01-012020-12-310000092122so:CommonStockholdersEquityNotIncludingNoncontrollingInterestMemberso:SouthernPowerMember2020-01-012020-12-310000092122us-gaap:NoncontrollingInterestMemberso:SouthernPowerMember2020-01-012020-12-310000092122us-gaap:AdditionalPaidInCapitalMemberso:SouthernPowerMember2020-01-012020-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:SouthernPowerMember2020-01-012020-12-310000092122us-gaap:AdditionalPaidInCapitalMemberso:SouthernPowerMember2020-12-310000092122us-gaap:RetainedEarningsMemberso:SouthernPowerMember2020-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:SouthernPowerMember2020-12-310000092122so:CommonStockholdersEquityNotIncludingNoncontrollingInterestMemberso:SouthernPowerMember2020-12-310000092122us-gaap:NoncontrollingInterestMemberso:SouthernPowerMember2020-12-310000092122us-gaap:RetainedEarningsMemberso:SouthernPowerMember2021-01-012021-12-310000092122so:CommonStockholdersEquityNotIncludingNoncontrollingInterestMemberso:SouthernPowerMember2021-01-012021-12-310000092122us-gaap:NoncontrollingInterestMemberso:SouthernPowerMember2021-01-012021-12-310000092122us-gaap:AdditionalPaidInCapitalMemberso:SouthernPowerMember2021-01-012021-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:SouthernPowerMember2021-01-012021-12-310000092122us-gaap:AdditionalPaidInCapitalMemberso:SouthernPowerMember2021-12-310000092122us-gaap:RetainedEarningsMemberso:SouthernPowerMember2021-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:SouthernPowerMember2021-12-310000092122so:CommonStockholdersEquityNotIncludingNoncontrollingInterestMemberso:SouthernPowerMember2021-12-310000092122us-gaap:NoncontrollingInterestMemberso:SouthernPowerMember2021-12-310000092122so:SouthernCompanyGasMember2020-01-012020-12-310000092122so:SouthernCompanyGasMember2019-01-012019-12-310000092122so:SouthernCompanyGasMemberus-gaap:NaturalGasUsRegulatedMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberus-gaap:NaturalGasUsRegulatedMember2020-01-012020-12-310000092122so:SouthernCompanyGasMemberus-gaap:NaturalGasUsRegulatedMember2019-01-012019-12-310000092122us-gaap:AlternativeEnergyMemberso:SouthernCompanyGasMember2021-01-012021-12-310000092122us-gaap:AlternativeEnergyMemberso:SouthernCompanyGasMember2020-01-012020-12-310000092122us-gaap:AlternativeEnergyMemberso:SouthernCompanyGasMember2019-01-012019-12-310000092122so:SouthernCompanyGasMember2020-12-310000092122so:SouthernCompanyGasMember2019-12-310000092122so:SouthernCompanyGasMember2018-12-310000092122so:SouthernCompanyGasMember2021-12-310000092122us-gaap:AdditionalPaidInCapitalMemberso:SouthernCompanyGasMember2018-12-310000092122us-gaap:RetainedEarningsMemberso:SouthernCompanyGasMember2018-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:SouthernCompanyGasMember2018-12-310000092122us-gaap:RetainedEarningsMemberso:SouthernCompanyGasMember2019-01-012019-12-310000092122us-gaap:AdditionalPaidInCapitalMemberso:SouthernCompanyGasMember2019-01-012019-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:SouthernCompanyGasMember2019-01-012019-12-310000092122us-gaap:AdditionalPaidInCapitalMemberso:SouthernCompanyGasMember2019-12-310000092122us-gaap:RetainedEarningsMemberso:SouthernCompanyGasMember2019-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:SouthernCompanyGasMember2019-12-310000092122us-gaap:RetainedEarningsMemberso:SouthernCompanyGasMember2020-01-012020-12-310000092122us-gaap:AdditionalPaidInCapitalMemberso:SouthernCompanyGasMember2020-01-012020-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:SouthernCompanyGasMember2020-01-012020-12-310000092122us-gaap:AdditionalPaidInCapitalMemberso:SouthernCompanyGasMember2020-12-310000092122us-gaap:RetainedEarningsMemberso:SouthernCompanyGasMember2020-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:SouthernCompanyGasMember2020-12-310000092122us-gaap:RetainedEarningsMemberso:SouthernCompanyGasMember2021-01-012021-12-310000092122us-gaap:AdditionalPaidInCapitalMemberso:SouthernCompanyGasMember2021-01-012021-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:SouthernCompanyGasMember2021-01-012021-12-310000092122us-gaap:AdditionalPaidInCapitalMemberso:SouthernCompanyGasMember2021-12-310000092122us-gaap:RetainedEarningsMemberso:SouthernCompanyGasMember2021-12-310000092122us-gaap:AccumulatedOtherComprehensiveIncomeMemberso:SouthernCompanyGasMember2021-12-31so:company0000092122so:TraditionalOperatingCompaniesMember2021-12-31so:state0000092122so:AlabamaPowerMemberso:SouthernCompanyServicesIncMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:SouthernCompanyServicesIncMember2021-01-012021-12-310000092122so:MississippiPowerMemberso:SouthernCompanyServicesIncMember2021-01-012021-12-310000092122so:SouthernCompanyServicesIncMemberso:SouthernPowerMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberso:SouthernCompanyServicesIncMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:SouthernCompanyServicesIncMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:SouthernCompanyServicesIncMember2020-01-012020-12-310000092122so:MississippiPowerMemberso:SouthernCompanyServicesIncMember2020-01-012020-12-310000092122so:SouthernCompanyServicesIncMemberso:SouthernPowerMember2020-01-012020-12-310000092122so:SouthernCompanyGasMemberso:SouthernCompanyServicesIncMember2020-01-012020-12-310000092122so:AlabamaPowerMemberso:SouthernCompanyServicesIncMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:SouthernCompanyServicesIncMember2019-01-012019-12-310000092122so:MississippiPowerMemberso:SouthernCompanyServicesIncMember2019-01-012019-12-310000092122so:SouthernCompanyServicesIncMemberso:SouthernPowerMember2019-01-012019-12-310000092122so:SouthernCompanyGasMemberso:SouthernCompanyServicesIncMember2019-01-012019-12-310000092122so:AlabamaPowerMemberso:SouthernNuclearOperatingCompanyIncMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:SouthernNuclearOperatingCompanyIncMember2020-01-012020-12-310000092122so:AlabamaPowerMemberso:SouthernNuclearOperatingCompanyIncMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:SouthernNuclearOperatingCompanyIncMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:SouthernNuclearOperatingCompanyIncMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:SouthernNuclearOperatingCompanyIncMember2019-01-012019-12-310000092122so:AlabamaPowerMemberso:PowerPoolMemberso:MississippiPowerMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:PowerPoolMemberso:SouthernPowerMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:PowerPoolMemberso:MississippiPowerMember2020-01-012020-12-310000092122so:AlabamaPowerMemberso:PowerPoolMemberso:SouthernPowerMember2020-01-012020-12-310000092122so:AlabamaPowerMemberso:PowerPoolMemberso:MississippiPowerMember2019-01-012019-12-310000092122so:AlabamaPowerMemberso:PowerPoolMemberso:SouthernPowerMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:SouthernPowerMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:SouthernPowerMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:SouthernPowerMember2019-01-012019-12-310000092122so:PurchasedPowerFromAffiliatesMemberso:SouthernPowerMember2021-01-012021-12-310000092122so:PurchasedPowerFromAffiliatesMemberso:SouthernPowerMember2020-01-012020-12-310000092122so:PurchasedPowerFromAffiliatesMemberso:SouthernPowerMember2019-01-012019-12-310000092122so:OperatingLeasePpaMemberso:SouthernPowerMember2021-01-012021-12-310000092122so:OperatingLeasePpaMemberso:SouthernPowerMember2020-01-012020-12-310000092122so:OperatingLeasePpaMemberso:SouthernPowerMember2019-01-012019-12-310000092122so:AlabamaPowerMemberso:SouthernNaturalGasCompanyLLCMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:SouthernNaturalGasCompanyLLCMember2021-01-012021-12-310000092122so:SouthernNaturalGasCompanyLLCMemberso:SouthernPowerMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberso:SouthernNaturalGasCompanyLLCMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:SouthernNaturalGasCompanyLLCMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:SouthernNaturalGasCompanyLLCMember2020-01-012020-12-310000092122so:SouthernNaturalGasCompanyLLCMemberso:SouthernPowerMember2020-01-012020-12-310000092122so:SouthernCompanyGasMemberso:SouthernNaturalGasCompanyLLCMember2020-01-012020-12-310000092122so:AlabamaPowerMemberso:SouthernNaturalGasCompanyLLCMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:SouthernNaturalGasCompanyLLCMember2019-01-012019-12-310000092122so:SouthernNaturalGasCompanyLLCMemberso:SouthernPowerMember2019-01-012019-12-310000092122so:SouthernCompanyGasMemberso:SouthernNaturalGasCompanyLLCMember2019-01-012019-12-310000092122so:SouthernCompanyGasMemberso:SouthernPowerMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberso:SouthernPowerMember2020-01-012020-12-310000092122so:SouthernCompanyGasMemberso:SouthernPowerMember2019-01-012019-12-310000092122so:NonFuelExpenseMemberso:AlabamaPowerMemberso:MississippiPowerMember2021-01-012021-12-310000092122so:NonFuelExpenseMemberso:AlabamaPowerMemberso:MississippiPowerMember2020-01-012020-12-310000092122so:NonFuelExpenseMemberso:AlabamaPowerMemberso:MississippiPowerMember2019-01-012019-12-310000092122so:SouthernCompanyServicesIncMemberso:SouthernPowerMemberus-gaap:ElectricTransmissionMember2021-01-012021-12-310000092122so:SouthernCompanyServicesIncMemberso:SouthernPowerMemberus-gaap:ElectricTransmissionMember2020-01-012020-12-310000092122so:SouthernCompanyServicesIncMemberso:SouthernPowerMemberus-gaap:ElectricTransmissionMember2019-01-012019-12-310000092122so:PowerSecureInternationalInc.Memberso:AlabamaPowerMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:PowerSecureInternationalInc.Member2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:PowerSecureInternationalInc.Member2019-01-012019-12-310000092122so:SouthernCompanyGasMemberso:IncludedInOperatingExpensesMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberso:IncludedInOperatingExpensesMember2020-01-012020-12-310000092122so:SouthernCompanyGasMemberso:IncludedInOperatingExpensesMember2019-01-012019-12-310000092122so:AtlantaGasLightMember2021-12-310000092122so:AtlantaGasLightMember2020-12-310000092122so:AtlantaGasLightMember2019-12-310000092122so:ChattanoogaGasMember2021-12-310000092122so:ChattanoogaGasMember2020-12-310000092122so:ChattanoogaGasMember2019-12-310000092122so:NicorGasMember2021-12-310000092122so:NicorGasMember2020-12-310000092122so:NicorGasMember2019-12-3100000921222021-10-012021-12-310000092122so:SouthernCompanyGasMember2021-10-012021-12-310000092122so:GasDistributionOperationsMemberso:SouthernCompanyGasMember2020-12-310000092122so:GasDistributionOperationsMemberso:SouthernCompanyGasMember2021-12-310000092122so:GasMarketingServicesMemberso:SouthernCompanyGasMember2021-12-310000092122so:GasMarketingServicesMemberso:SouthernCompanyGasMember2020-12-310000092122us-gaap:CustomerRelationshipsMember2021-12-310000092122us-gaap:CustomerRelationshipsMember2020-12-310000092122us-gaap:TradeNamesMember2021-12-310000092122us-gaap:TradeNamesMember2020-12-310000092122so:StorageandTransportationContractsMember2021-12-310000092122so:StorageandTransportationContractsMember2020-12-310000092122so:PPAFairValueAdjustmentsMember2021-12-310000092122so:PPAFairValueAdjustmentsMember2020-12-310000092122us-gaap:OtherIntangibleAssetsMember2021-12-310000092122us-gaap:OtherIntangibleAssetsMember2020-12-310000092122so:FCCLicensesMember2021-12-310000092122so:FCCLicensesMember2020-12-310000092122so:PPAFairValueAdjustmentsMemberso:SouthernPowerMember2021-12-310000092122so:PPAFairValueAdjustmentsMemberso:SouthernPowerMember2020-12-310000092122so:SouthernCompanyGasMemberus-gaap:CustomerRelationshipsMember2021-12-310000092122so:SouthernCompanyGasMemberus-gaap:CustomerRelationshipsMember2020-12-310000092122so:SouthernCompanyGasMemberus-gaap:TradeNamesMember2021-12-310000092122so:SouthernCompanyGasMemberus-gaap:TradeNamesMember2020-12-310000092122so:SouthernCompanyGasMemberso:StorageandTransportationContractsMember2021-12-310000092122so:SouthernCompanyGasMemberso:StorageandTransportationContractsMember2020-12-310000092122so:GasMarketingServicesMemberso:SouthernCompanyGasMember2021-01-012021-12-310000092122so:GasMarketingServicesMemberso:SouthernCompanyGasMember2020-01-012020-12-310000092122so:GasMarketingServicesMemberso:SouthernCompanyGasMember2019-01-012019-12-310000092122so:WholesaleGasServicesMemberso:SouthernCompanyGasMember2021-01-012021-12-310000092122so:WholesaleGasServicesMemberso:SouthernCompanyGasMember2020-01-012020-12-310000092122so:WholesaleGasServicesMemberso:SouthernCompanyGasMember2019-01-012019-12-310000092122so:OperatingRevenuesMember2021-01-012021-12-310000092122so:OperatingRevenuesMember2020-01-012020-12-310000092122so:OperatingRevenuesMember2019-01-012019-12-310000092122so:SouthernCompanyGasMemberso:IntangibleLiabilitiesMember2019-12-310000092122us-gaap:OtherCurrentAssetsMember2021-12-310000092122us-gaap:OtherCurrentAssetsMember2020-12-310000092122us-gaap:OtherCurrentAssetsMemberso:SouthernPowerMember2021-12-310000092122so:SouthernCompanyGasMemberus-gaap:OtherCurrentAssetsMember2021-12-310000092122so:SouthernCompanyGasMemberus-gaap:OtherCurrentAssetsMember2020-12-310000092122us-gaap:OtherNoncurrentAssetsMember2021-12-310000092122us-gaap:OtherNoncurrentAssetsMember2020-12-310000092122us-gaap:OtherNoncurrentAssetsMemberso:SouthernPowerMember2021-12-310000092122us-gaap:OtherNoncurrentAssetsMemberso:SouthernCompanyGasMember2021-12-310000092122us-gaap:OtherNoncurrentAssetsMemberso:SouthernCompanyGasMember2020-12-310000092122so:GarlandMemberso:TaxEquityContributionsMemberso:SouthernPowerMember2021-12-310000092122so:DeuelHarvestMemberso:EstimatedConstructionCompletionCostsMemberso:SouthernPowerMember2021-12-310000092122so:AlabamaPowerMemberso:MajorStormMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:MajorStormMember2020-01-012020-12-310000092122so:AlabamaPowerMemberso:MajorStormMember2019-01-012019-12-310000092122so:MajorStormMember2021-01-012021-12-310000092122so:MississippiPowerMemberso:MajorStormMember2021-01-012021-12-310000092122so:MajorStormMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:MajorStormMember2020-01-012020-12-310000092122so:MississippiPowerMemberso:MajorStormMember2020-01-012020-12-310000092122so:MajorStormMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:MajorStormMember2019-01-012019-12-310000092122so:MississippiPowerMemberso:MajorStormMember2019-01-012019-12-310000092122so:AlabamaPowerMemberso:MajorStormMemberso:AccumulatedDeferredIncomeTaxesMember2020-01-012020-12-31so:customer0000092122us-gaap:AccumulatedGainLossNetCashFlowHedgeParentMember2020-12-310000092122us-gaap:AccumulatedDefinedBenefitPlansAdjustmentMember2020-12-310000092122us-gaap:AccumulatedGainLossNetCashFlowHedgeParentMember2021-01-012021-12-310000092122us-gaap:AccumulatedDefinedBenefitPlansAdjustmentMember2021-01-012021-12-310000092122us-gaap:AccumulatedGainLossNetCashFlowHedgeParentMember2021-12-310000092122us-gaap:AccumulatedDefinedBenefitPlansAdjustmentMember2021-12-310000092122us-gaap:AccumulatedGainLossNetCashFlowHedgeParentMemberso:SouthernPowerMember2020-12-310000092122us-gaap:AccumulatedDefinedBenefitPlansAdjustmentMemberso:SouthernPowerMember2020-12-310000092122us-gaap:AccumulatedGainLossNetCashFlowHedgeParentMemberso:SouthernPowerMember2021-01-012021-12-310000092122us-gaap:AccumulatedDefinedBenefitPlansAdjustmentMemberso:SouthernPowerMember2021-01-012021-12-310000092122us-gaap:AccumulatedGainLossNetCashFlowHedgeParentMemberso:SouthernPowerMember2021-12-310000092122us-gaap:AccumulatedDefinedBenefitPlansAdjustmentMemberso:SouthernPowerMember2021-12-310000092122so:SouthernCompanyGasMemberus-gaap:AccumulatedGainLossNetCashFlowHedgeParentMember2020-12-310000092122us-gaap:AccumulatedDefinedBenefitPlansAdjustmentMemberso:SouthernCompanyGasMember2020-12-310000092122so:SouthernCompanyGasMemberus-gaap:AccumulatedGainLossNetCashFlowHedgeParentMember2021-01-012021-12-310000092122us-gaap:AccumulatedDefinedBenefitPlansAdjustmentMemberso:SouthernCompanyGasMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberus-gaap:AccumulatedGainLossNetCashFlowHedgeParentMember2021-12-310000092122us-gaap:AccumulatedDefinedBenefitPlansAdjustmentMemberso:SouthernCompanyGasMember2021-12-310000092122us-gaap:AssetRetirementObligationCostsMember2021-12-310000092122us-gaap:AssetRetirementObligationCostsMemberso:AlabamaPowerMember2021-12-310000092122so:GeorgiaPowerMemberus-gaap:AssetRetirementObligationCostsMember2021-12-310000092122us-gaap:AssetRetirementObligationCostsMemberso:MississippiPowerMember2021-12-310000092122us-gaap:AssetRetirementObligationCostsMemberso:SouthernCompanyGasMember2021-12-310000092122so:RetireeBenefitPlansMember2021-12-310000092122so:AlabamaPowerMemberso:RetireeBenefitPlansMember2021-12-310000092122so:GeorgiaPowerMemberso:RetireeBenefitPlansMember2021-12-310000092122so:RetireeBenefitPlansMemberso:MississippiPowerMember2021-12-310000092122so:RetireeBenefitPlansMemberso:SouthernCompanyGasMember2021-12-310000092122so:RemainingNetBookValueOfRetiredAssetsMember2021-12-310000092122so:AlabamaPowerMemberso:RemainingNetBookValueOfRetiredAssetsMember2021-12-310000092122so:GeorgiaPowerMemberso:RemainingNetBookValueOfRetiredAssetsMember2021-12-310000092122so:RemainingNetBookValueOfRetiredAssetsMemberso:MississippiPowerMember2021-12-310000092122so:RemainingNetBookValueOfRetiredAssetsMemberso:SouthernCompanyGasMember2021-12-310000092122us-gaap:DeferredIncomeTaxChargesMember2021-12-310000092122so:AlabamaPowerMemberus-gaap:DeferredIncomeTaxChargesMember2021-12-310000092122so:GeorgiaPowerMemberus-gaap:DeferredIncomeTaxChargesMember2021-12-310000092122so:MississippiPowerMemberus-gaap:DeferredIncomeTaxChargesMember2021-12-310000092122so:SouthernCompanyGasMemberus-gaap:DeferredIncomeTaxChargesMember2021-12-310000092122us-gaap:RegulatoryClauseRevenuesUnderRecoveredMember2021-12-310000092122so:AlabamaPowerMemberus-gaap:RegulatoryClauseRevenuesUnderRecoveredMember2021-12-310000092122so:GeorgiaPowerMemberus-gaap:RegulatoryClauseRevenuesUnderRecoveredMember2021-12-310000092122so:MississippiPowerMemberus-gaap:RegulatoryClauseRevenuesUnderRecoveredMember2021-12-310000092122so:SouthernCompanyGasMemberus-gaap:RegulatoryClauseRevenuesUnderRecoveredMember2021-12-310000092122us-gaap:EnvironmentalRestorationCostsMember2021-12-310000092122us-gaap:EnvironmentalRestorationCostsMemberso:AlabamaPowerMember2021-12-310000092122us-gaap:EnvironmentalRestorationCostsMemberso:GeorgiaPowerMember2021-12-310000092122us-gaap:EnvironmentalRestorationCostsMemberso:MississippiPowerMember2021-12-310000092122us-gaap:EnvironmentalRestorationCostsMemberso:SouthernCompanyGasMember2021-12-310000092122us-gaap:LossOnReacquiredDebtMember2021-12-310000092122us-gaap:LossOnReacquiredDebtMemberso:AlabamaPowerMember2021-12-310000092122us-gaap:LossOnReacquiredDebtMemberso:GeorgiaPowerMember2021-12-310000092122us-gaap:LossOnReacquiredDebtMemberso:MississippiPowerMember2021-12-310000092122us-gaap:LossOnReacquiredDebtMemberso:SouthernCompanyGasMember2021-12-310000092122us-gaap:RecoverableVacationPayMember2021-12-310000092122us-gaap:RecoverableVacationPayMemberso:AlabamaPowerMember2021-12-310000092122so:GeorgiaPowerMemberus-gaap:RecoverableVacationPayMember2021-12-310000092122us-gaap:RecoverableVacationPayMemberso:MississippiPowerMember2021-12-310000092122us-gaap:RecoverableVacationPayMemberso:SouthernCompanyGasMember2021-12-310000092122so:RegulatoryClausesMember2021-12-310000092122so:AlabamaPowerMemberso:RegulatoryClausesMember2021-12-310000092122so:GeorgiaPowerMemberso:RegulatoryClausesMember2021-12-310000092122so:MississippiPowerMemberso:RegulatoryClausesMember2021-12-310000092122so:SouthernCompanyGasMemberso:RegulatoryClausesMember2021-12-310000092122so:PropertyDamageReservesAssetMember2021-12-310000092122so:AlabamaPowerMemberso:PropertyDamageReservesAssetMember2021-12-310000092122so:GeorgiaPowerMemberso:PropertyDamageReservesAssetMember2021-12-310000092122so:MississippiPowerMemberso:PropertyDamageReservesAssetMember2021-12-310000092122so:SouthernCompanyGasMemberso:PropertyDamageReservesAssetMember2021-12-310000092122so:LongTermDebtFairValueAdjustmentMember2021-12-310000092122so:AlabamaPowerMemberso:LongTermDebtFairValueAdjustmentMember2021-12-310000092122so:GeorgiaPowerMemberso:LongTermDebtFairValueAdjustmentMember2021-12-310000092122so:MississippiPowerMemberso:LongTermDebtFairValueAdjustmentMember2021-12-310000092122so:SouthernCompanyGasMemberso:LongTermDebtFairValueAdjustmentMember2021-12-310000092122so:NuclearOutageMember2021-12-310000092122so:AlabamaPowerMemberso:NuclearOutageMember2021-12-310000092122so:GeorgiaPowerMemberso:NuclearOutageMember2021-12-310000092122so:NuclearOutageMemberso:MississippiPowerMember2021-12-310000092122so:NuclearOutageMemberso:SouthernCompanyGasMember2021-12-310000092122so:SoftwareAndCloudComputingCostsMember2021-12-310000092122so:SoftwareAndCloudComputingCostsMemberso:AlabamaPowerMember2021-12-310000092122so:SoftwareAndCloudComputingCostsMemberso:GeorgiaPowerMember2021-12-310000092122so:SoftwareAndCloudComputingCostsMemberso:MississippiPowerMember2021-12-310000092122so:SoftwareAndCloudComputingCostsMemberso:SouthernCompanyGasMember2021-12-310000092122so:KemperIgccMember2021-12-310000092122so:AlabamaPowerMemberso:KemperIgccMember2021-12-310000092122so:GeorgiaPowerMemberso:KemperIgccMember2021-12-310000092122so:KemperIgccMemberso:MississippiPowerMember2021-12-310000092122so:KemperIgccMemberso:SouthernCompanyGasMember2021-12-310000092122so:PlantDanielUnitsThreeAndFourMember2021-12-310000092122so:PlantDanielUnitsThreeAndFourMemberso:AlabamaPowerMember2021-12-310000092122so:GeorgiaPowerMemberso:PlantDanielUnitsThreeAndFourMember2021-12-310000092122so:PlantDanielUnitsThreeAndFourMemberso:MississippiPowerMember2021-12-310000092122so:PlantDanielUnitsThreeAndFourMemberso:SouthernCompanyGasMember2021-12-310000092122so:OtherRegulatoryAssetsMember2021-12-310000092122so:AlabamaPowerMemberso:OtherRegulatoryAssetsMember2021-12-310000092122so:GeorgiaPowerMemberso:OtherRegulatoryAssetsMember2021-12-310000092122so:OtherRegulatoryAssetsMemberso:MississippiPowerMember2021-12-310000092122so:OtherRegulatoryAssetsMemberso:SouthernCompanyGasMember2021-12-310000092122so:DeferredIncomeTaxCreditsMember2021-12-310000092122so:AlabamaPowerMemberso:DeferredIncomeTaxCreditsMember2021-12-310000092122so:GeorgiaPowerMemberso:DeferredIncomeTaxCreditsMember2021-12-310000092122so:MississippiPowerMemberso:DeferredIncomeTaxCreditsMember2021-12-310000092122so:SouthernCompanyGasMemberso:DeferredIncomeTaxCreditsMember2021-12-310000092122so:OtherCostOfRemovalObligationsMember2021-12-310000092122so:AlabamaPowerMemberso:OtherCostOfRemovalObligationsMember2021-12-310000092122so:GeorgiaPowerMemberso:OtherCostOfRemovalObligationsMember2021-12-310000092122so:MississippiPowerMemberso:OtherCostOfRemovalObligationsMember2021-12-310000092122so:SouthernCompanyGasMemberso:OtherCostOfRemovalObligationsMember2021-12-310000092122so:CustomerRefundsMember2021-12-310000092122so:AlabamaPowerMemberso:CustomerRefundsMember2021-12-310000092122so:GeorgiaPowerMemberso:CustomerRefundsMember2021-12-310000092122so:CustomerRefundsMemberso:MississippiPowerMember2021-12-310000092122so:CustomerRefundsMemberso:SouthernCompanyGasMember2021-12-310000092122so:FuelHedgingRealizedAndUnrealizedLossesMember2021-12-310000092122so:FuelHedgingRealizedAndUnrealizedLossesMemberso:AlabamaPowerMember2021-12-310000092122so:GeorgiaPowerMemberso:FuelHedgingRealizedAndUnrealizedLossesMember2021-12-310000092122so:FuelHedgingRealizedAndUnrealizedLossesMemberso:MississippiPowerMember2021-12-310000092122so:FuelHedgingRealizedAndUnrealizedLossesMemberso:SouthernCompanyGasMember2021-12-310000092122so:StormAndPropertyDamageReservesLiabilityMember2021-12-310000092122so:AlabamaPowerMemberso:StormAndPropertyDamageReservesLiabilityMember2021-12-310000092122so:GeorgiaPowerMemberso:StormAndPropertyDamageReservesLiabilityMember2021-12-310000092122so:StormAndPropertyDamageReservesLiabilityMemberso:MississippiPowerMember2021-12-310000092122so:StormAndPropertyDamageReservesLiabilityMemberso:SouthernCompanyGasMember2021-12-310000092122so:OverRecoveredRegulatoryClauseRevenuesMember2021-12-310000092122so:AlabamaPowerMemberso:OverRecoveredRegulatoryClauseRevenuesMember2021-12-310000092122so:GeorgiaPowerMemberso:OverRecoveredRegulatoryClauseRevenuesMember2021-12-310000092122so:MississippiPowerMemberso:OverRecoveredRegulatoryClauseRevenuesMember2021-12-310000092122so:SouthernCompanyGasMemberso:OverRecoveredRegulatoryClauseRevenuesMember2021-12-310000092122so:OtherRegulatoryLiabilitiesMember2021-12-310000092122so:OtherRegulatoryLiabilitiesMemberso:AlabamaPowerMember2021-12-310000092122so:OtherRegulatoryLiabilitiesMemberso:GeorgiaPowerMember2021-12-310000092122so:OtherRegulatoryLiabilitiesMemberso:MississippiPowerMember2021-12-310000092122so:OtherRegulatoryLiabilitiesMemberso:SouthernCompanyGasMember2021-12-310000092122us-gaap:AssetRetirementObligationCostsMember2020-12-310000092122us-gaap:AssetRetirementObligationCostsMemberso:AlabamaPowerMember2020-12-310000092122so:GeorgiaPowerMemberus-gaap:AssetRetirementObligationCostsMember2020-12-310000092122us-gaap:AssetRetirementObligationCostsMemberso:MississippiPowerMember2020-12-310000092122us-gaap:AssetRetirementObligationCostsMemberso:SouthernCompanyGasMember2020-12-310000092122so:RetireeBenefitPlansMember2020-12-310000092122so:AlabamaPowerMemberso:RetireeBenefitPlansMember2020-12-310000092122so:GeorgiaPowerMemberso:RetireeBenefitPlansMember2020-12-310000092122so:RetireeBenefitPlansMemberso:MississippiPowerMember2020-12-310000092122so:RetireeBenefitPlansMemberso:SouthernCompanyGasMember2020-12-310000092122so:RemainingNetBookValueOfRetiredAssetsMember2020-12-310000092122so:AlabamaPowerMemberso:RemainingNetBookValueOfRetiredAssetsMember2020-12-310000092122so:GeorgiaPowerMemberso:RemainingNetBookValueOfRetiredAssetsMember2020-12-310000092122so:RemainingNetBookValueOfRetiredAssetsMemberso:MississippiPowerMember2020-12-310000092122so:RemainingNetBookValueOfRetiredAssetsMemberso:SouthernCompanyGasMember2020-12-310000092122us-gaap:DeferredIncomeTaxChargesMember2020-12-310000092122so:AlabamaPowerMemberus-gaap:DeferredIncomeTaxChargesMember2020-12-310000092122so:GeorgiaPowerMemberus-gaap:DeferredIncomeTaxChargesMember2020-12-310000092122so:MississippiPowerMemberus-gaap:DeferredIncomeTaxChargesMember2020-12-310000092122so:SouthernCompanyGasMemberus-gaap:DeferredIncomeTaxChargesMember2020-12-310000092122us-gaap:EnvironmentalRestorationCostsMember2020-12-310000092122us-gaap:EnvironmentalRestorationCostsMemberso:AlabamaPowerMember2020-12-310000092122us-gaap:EnvironmentalRestorationCostsMemberso:GeorgiaPowerMember2020-12-310000092122us-gaap:EnvironmentalRestorationCostsMemberso:MississippiPowerMember2020-12-310000092122us-gaap:EnvironmentalRestorationCostsMemberso:SouthernCompanyGasMember2020-12-310000092122us-gaap:LossOnReacquiredDebtMember2020-12-310000092122us-gaap:LossOnReacquiredDebtMemberso:AlabamaPowerMember2020-12-310000092122us-gaap:LossOnReacquiredDebtMemberso:GeorgiaPowerMember2020-12-310000092122us-gaap:LossOnReacquiredDebtMemberso:MississippiPowerMember2020-12-310000092122us-gaap:LossOnReacquiredDebtMemberso:SouthernCompanyGasMember2020-12-310000092122so:PropertyDamageReservesAssetMember2020-12-310000092122so:AlabamaPowerMemberso:PropertyDamageReservesAssetMember2020-12-310000092122so:GeorgiaPowerMemberso:PropertyDamageReservesAssetMember2020-12-310000092122so:MississippiPowerMemberso:PropertyDamageReservesAssetMember2020-12-310000092122so:SouthernCompanyGasMemberso:PropertyDamageReservesAssetMember2020-12-310000092122us-gaap:RecoverableVacationPayMember2020-12-310000092122us-gaap:RecoverableVacationPayMemberso:AlabamaPowerMember2020-12-310000092122so:GeorgiaPowerMemberus-gaap:RecoverableVacationPayMember2020-12-310000092122us-gaap:RecoverableVacationPayMemberso:MississippiPowerMember2020-12-310000092122us-gaap:RecoverableVacationPayMemberso:SouthernCompanyGasMember2020-12-310000092122us-gaap:RegulatoryClauseRevenuesUnderRecoveredMember2020-12-310000092122so:AlabamaPowerMemberus-gaap:RegulatoryClauseRevenuesUnderRecoveredMember2020-12-310000092122so:GeorgiaPowerMemberus-gaap:RegulatoryClauseRevenuesUnderRecoveredMember2020-12-310000092122so:MississippiPowerMemberus-gaap:RegulatoryClauseRevenuesUnderRecoveredMember2020-12-310000092122so:SouthernCompanyGasMemberus-gaap:RegulatoryClauseRevenuesUnderRecoveredMember2020-12-310000092122so:RegulatoryClausesMember2020-12-310000092122so:AlabamaPowerMemberso:RegulatoryClausesMember2020-12-310000092122so:GeorgiaPowerMemberso:RegulatoryClausesMember2020-12-310000092122so:MississippiPowerMemberso:RegulatoryClausesMember2020-12-310000092122so:SouthernCompanyGasMemberso:RegulatoryClausesMember2020-12-310000092122so:NuclearOutageMember2020-12-310000092122so:AlabamaPowerMemberso:NuclearOutageMember2020-12-310000092122so:GeorgiaPowerMemberso:NuclearOutageMember2020-12-310000092122so:NuclearOutageMemberso:MississippiPowerMember2020-12-310000092122so:NuclearOutageMemberso:SouthernCompanyGasMember2020-12-310000092122so:LongTermDebtFairValueAdjustmentMember2020-12-310000092122so:AlabamaPowerMemberso:LongTermDebtFairValueAdjustmentMember2020-12-310000092122so:GeorgiaPowerMemberso:LongTermDebtFairValueAdjustmentMember2020-12-310000092122so:MississippiPowerMemberso:LongTermDebtFairValueAdjustmentMember2020-12-310000092122so:SouthernCompanyGasMemberso:LongTermDebtFairValueAdjustmentMember2020-12-310000092122so:KemperIgccMember2020-12-310000092122so:AlabamaPowerMemberso:KemperIgccMember2020-12-310000092122so:GeorgiaPowerMemberso:KemperIgccMember2020-12-310000092122so:KemperIgccMemberso:MississippiPowerMember2020-12-310000092122so:KemperIgccMemberso:SouthernCompanyGasMember2020-12-310000092122so:PlantDanielUnitsThreeAndFourMember2020-12-310000092122so:PlantDanielUnitsThreeAndFourMemberso:AlabamaPowerMember2020-12-310000092122so:GeorgiaPowerMemberso:PlantDanielUnitsThreeAndFourMember2020-12-310000092122so:PlantDanielUnitsThreeAndFourMemberso:MississippiPowerMember2020-12-310000092122so:PlantDanielUnitsThreeAndFourMemberso:SouthernCompanyGasMember2020-12-310000092122so:SoftwareAndCloudComputingCostsMember2020-12-310000092122so:SoftwareAndCloudComputingCostsMemberso:AlabamaPowerMember2020-12-310000092122so:SoftwareAndCloudComputingCostsMemberso:GeorgiaPowerMember2020-12-310000092122so:SoftwareAndCloudComputingCostsMemberso:MississippiPowerMember2020-12-310000092122so:SoftwareAndCloudComputingCostsMemberso:SouthernCompanyGasMember2020-12-310000092122so:OtherRegulatoryAssetsMember2020-12-310000092122so:AlabamaPowerMemberso:OtherRegulatoryAssetsMember2020-12-310000092122so:GeorgiaPowerMemberso:OtherRegulatoryAssetsMember2020-12-310000092122so:OtherRegulatoryAssetsMemberso:MississippiPowerMember2020-12-310000092122so:OtherRegulatoryAssetsMemberso:SouthernCompanyGasMember2020-12-310000092122so:DeferredIncomeTaxCreditsMember2020-12-310000092122so:AlabamaPowerMemberso:DeferredIncomeTaxCreditsMember2020-12-310000092122so:GeorgiaPowerMemberso:DeferredIncomeTaxCreditsMember2020-12-310000092122so:MississippiPowerMemberso:DeferredIncomeTaxCreditsMember2020-12-310000092122so:SouthernCompanyGasMemberso:DeferredIncomeTaxCreditsMember2020-12-310000092122so:OtherCostOfRemovalObligationsMember2020-12-310000092122so:AlabamaPowerMemberso:OtherCostOfRemovalObligationsMember2020-12-310000092122so:GeorgiaPowerMemberso:OtherCostOfRemovalObligationsMember2020-12-310000092122so:MississippiPowerMemberso:OtherCostOfRemovalObligationsMember2020-12-310000092122so:SouthernCompanyGasMemberso:OtherCostOfRemovalObligationsMember2020-12-310000092122so:OverRecoveredRegulatoryClauseRevenuesMember2020-12-310000092122so:AlabamaPowerMemberso:OverRecoveredRegulatoryClauseRevenuesMember2020-12-310000092122so:GeorgiaPowerMemberso:OverRecoveredRegulatoryClauseRevenuesMember2020-12-310000092122so:MississippiPowerMemberso:OverRecoveredRegulatoryClauseRevenuesMember2020-12-310000092122so:SouthernCompanyGasMemberso:OverRecoveredRegulatoryClauseRevenuesMember2020-12-310000092122so:StormAndPropertyDamageReservesLiabilityMember2020-12-310000092122so:AlabamaPowerMemberso:StormAndPropertyDamageReservesLiabilityMember2020-12-310000092122so:GeorgiaPowerMemberso:StormAndPropertyDamageReservesLiabilityMember2020-12-310000092122so:StormAndPropertyDamageReservesLiabilityMemberso:MississippiPowerMember2020-12-310000092122so:StormAndPropertyDamageReservesLiabilityMemberso:SouthernCompanyGasMember2020-12-310000092122so:CustomerRefundsMember2020-12-310000092122so:AlabamaPowerMemberso:CustomerRefundsMember2020-12-310000092122so:GeorgiaPowerMemberso:CustomerRefundsMember2020-12-310000092122so:CustomerRefundsMemberso:MississippiPowerMember2020-12-310000092122so:CustomerRefundsMemberso:SouthernCompanyGasMember2020-12-310000092122so:OtherRegulatoryLiabilitiesMember2020-12-310000092122so:OtherRegulatoryLiabilitiesMemberso:AlabamaPowerMember2020-12-310000092122so:OtherRegulatoryLiabilitiesMemberso:GeorgiaPowerMember2020-12-310000092122so:OtherRegulatoryLiabilitiesMemberso:MississippiPowerMember2020-12-310000092122so:OtherRegulatoryLiabilitiesMemberso:SouthernCompanyGasMember2020-12-310000092122us-gaap:AssetRetirementObligationCostsMemberso:AlabamaPowerMembersrt:MaximumMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberus-gaap:AssetRetirementObligationCostsMembersrt:MaximumMember2021-01-012021-12-310000092122us-gaap:AssetRetirementObligationCostsMembersrt:MaximumMemberso:MississippiPowerMember2021-01-012021-12-310000092122us-gaap:AssetRetirementObligationCostsMembersrt:MaximumMemberso:SouthernCompanyGasMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:CCRAssetRetirementObligationsCostMembersrt:MaximumMember2021-01-012021-12-310000092122so:RetireeBenefitPlansMembersrt:MaximumMemberso:MississippiPowerMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:RetireeBenefitPlansMembersrt:MaximumMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:RetireeBenefitPlansMembersrt:MaximumMember2021-01-012021-12-310000092122so:RetireeBenefitPlansMembersrt:MaximumMemberso:SouthernCompanyGasMember2021-01-012021-12-310000092122so:PlantGorgasUnits89And10Memberso:AlabamaPowerMemberso:RemainingNetBookValueOfRetiredAssetsMember2021-12-310000092122so:PlantGorgasUnits89And10Memberso:AlabamaPowerMemberso:RemainingNetBookValueOfRetiredAssetsMembersrt:MaximumMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:RemainingNetBookValueOfRetiredAssetsMemberso:PlantHammondUnits1Through4AndPlantBranchUnits2Through4Member2021-12-310000092122so:GeorgiaPowerMemberso:RemainingNetBookValueOfRetiredAssetsMembersrt:MinimumMemberso:PlantHammondUnits1Through4AndPlantBranchUnits2Through4Member2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:RemainingNetBookValueOfRetiredAssetsMembersrt:MaximumMemberso:PlantHammondUnits1Through4AndPlantBranchUnits2Through4Member2021-01-012021-12-310000092122so:PlantMcIntoshUnit1AndPlantMitchellUnit3Memberso:GeorgiaPowerMemberso:RemainingNetBookValueOfRetiredAssetsMember2021-12-310000092122so:RemainingNetBookValueOfRetiredAssetsMemberso:MississippiPowerMemberso:WholesaleElectricRevenuesMemberso:PlantWatsonAndPlantGreeneCountyMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:RetireeMedicareDrugSubsidyMember2021-12-310000092122so:GeorgiaPowerMemberso:RetireeMedicareDrugSubsidyMember2021-12-310000092122so:GeorgiaPowerMemberus-gaap:DeferredIncomeTaxChargesMemberso:PlantVogtleUnits3And4Member2021-12-310000092122so:GeorgiaPowerMemberso:DeferredIncomeTaxCreditsMemberso:PlantVogtleUnits3And4Member2021-12-310000092122so:RetailElectricMemberso:MississippiPowerMemberso:DeferredIncomeTaxCreditsMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberso:ExcessDeferredIncomeTaxLiabilitiesNotSubjectToNormalizationMember2021-12-310000092122so:AlabamaPowerMemberus-gaap:RegulatoryClauseRevenuesUnderRecoveredMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberus-gaap:RegulatoryClauseRevenuesUnderRecoveredMember2021-01-012021-12-310000092122so:RegulatoryClausesAmortizedThroughPerformanceEvaluationPlanMemberso:MississippiPowerMember2021-12-310000092122so:RegulatoryClausesAmortizedThroughPerformanceEvaluationPlanMemberso:MississippiPowerMember2021-01-012021-12-310000092122so:PropertyTaxMemberso:MississippiPowerMember2021-12-310000092122so:SouthernCompanyGasMemberus-gaap:RegulatoryClauseRevenuesUnderRecoveredMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberso:OverRecoveredRegulatoryClauseRevenuesMember2021-01-012021-12-310000092122us-gaap:LossOnReacquiredDebtMemberso:AlabamaPowerMembersrt:MaximumMember2021-01-012021-12-310000092122us-gaap:LossOnReacquiredDebtMemberso:GeorgiaPowerMembersrt:MaximumMember2021-01-012021-12-310000092122us-gaap:LossOnReacquiredDebtMembersrt:MaximumMemberso:MississippiPowerMember2021-01-012021-12-310000092122us-gaap:LossOnReacquiredDebtMembersrt:MaximumMemberso:SouthernCompanyGasMember2021-01-012021-12-310000092122us-gaap:RecoverableVacationPayMember2021-01-012021-12-310000092122srt:MaximumMemberso:SouthernCompanyGasMemberso:LongTermDebtFairValueAdjustmentMember2021-01-012021-12-310000092122so:PlantFarleyMemberso:AlabamaPowerMemberso:NuclearOutageMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:NuclearOutageMembersrt:MaximumMemberso:PlantHatchNuclearMember2021-01-012021-12-310000092122so:SoftwareAndCloudComputingCostsMemberso:AlabamaPowerMember2021-01-012021-12-310000092122so:SoftwareAndCloudComputingCostsMemberso:SouthernCompanyGasMember2021-01-012021-12-310000092122so:RetailElectricMemberso:KemperIgccMemberso:MississippiPowerMember2021-12-310000092122so:KemperIgccMemberso:MississippiPowerMemberso:WholesaleElectricRevenuesMember2021-12-310000092122so:RetailElectricMemberso:PlantDanielUnitsThreeAndFourMember2021-12-310000092122so:PlantDanielUnitsThreeAndFourMemberso:WholesaleElectricRevenuesMember2021-12-310000092122so:AlabamaPowerMemberso:OtherRegulatoryAssetsMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:OtherRegulatoryAssetsMember2021-01-012021-12-310000092122so:OtherRegulatoryAssetsMemberso:MississippiPowerMember2021-01-012021-12-310000092122so:OtherRegulatoryAssetsMemberso:SouthernCompanyGasMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:FuelHedgingRealizedAndUnrealizedLossesMember2021-01-012021-12-310000092122so:FuelHedgingRealizedAndUnrealizedLossesMemberso:MississippiPowerMember2021-01-012021-12-310000092122so:OtherRegulatoryLiabilitiesMemberso:AlabamaPowerMember2021-01-012021-12-310000092122so:OtherRegulatoryLiabilitiesMemberso:GeorgiaPowerMember2021-01-012021-12-310000092122so:OtherRegulatoryLiabilitiesMemberso:MississippiPowerMember2021-01-012021-12-310000092122so:OtherRegulatoryLiabilitiesMemberso:SouthernCompanyGasMember2021-01-012021-12-310000092122so:FuelHedgingRealizedAndUnrealizedLossesMemberso:AlabamaPowerMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:PlantBarryUnit8Member2020-08-31utr:MW0000092122so:Year2020Memberso:AlabamaPowerMember2020-08-310000092122so:AlabamaPowerMember2020-08-310000092122so:AlabamaPowerMemberso:PlantBarryUnit8Member2021-12-310000092122so:Years2015Memberso:AlabamaPowerMember2021-12-310000092122so:CalhounPowerCompanyLLCMemberso:AlabamaPowerMember2021-09-230000092122so:CalhounPowerCompanyLLCMemberso:AlabamaPowerMember2021-09-232021-09-23so:projectso:agreement0000092122srt:ScenarioForecastMemberso:AlabamaPowerMember2024-01-012024-03-310000092122srt:ScenarioForecastMemberso:AlabamaPowerMember2025-01-012025-12-310000092122so:AlabamaPowerMember2019-01-012019-01-310000092122so:AlabamaPowerMembersrt:MinimumMember2021-01-012021-12-310000092122so:AlabamaPowerMembersrt:MaximumMember2021-01-012021-12-310000092122so:AlabamaPowerMembersrt:MinimumMember2019-01-012019-12-310000092122so:AlabamaPowerMembersrt:MinimumMember2020-01-012020-12-310000092122so:AlabamaPowerMember2021-01-01iso4217:USDso:KWH_Kilowatt_hour0000092122so:AlabamaPowerMember2018-01-012018-12-310000092122so:AlabamaPowerMember2019-12-012019-12-310000092122so:AlabamaPowerMember2020-10-012020-10-310000092122so:AlabamaPowerMember2020-12-012020-12-310000092122srt:ScenarioForecastMemberso:AlabamaPowerMember2023-01-012023-01-310000092122so:AlabamaPowerMemberso:SoftwareAccountingOrderMember2021-12-310000092122so:AlabamaPowerMemberso:SoftwareAccountingOrderMember2020-12-310000092122so:PlantGreeneCountyUnits1And2Memberso:MississippiPowerMember2021-09-090000092122srt:ScenarioForecastMemberso:AlabamaPowerMember2022-01-012022-12-310000092122srt:ScenarioForecastMemberso:AlabamaPowerMember2023-01-012023-12-310000092122so:GeorgiaPowerMemberso:TraditionalBaseMember2019-12-310000092122so:GeorgiaPowerMemberso:EnvironmentalComplianceCostRecoveryMember2019-12-310000092122so:GeorgiaPowerMemberso:DemandSideManagementMember2019-12-310000092122so:MunicipalFranchiseFeeMemberso:GeorgiaPowerMember2019-12-310000092122so:GeorgiaPowerMemberso:RemainingNetBookValueOfRetiredAssetsMembersrt:MaximumMember2019-01-012019-12-310000092122so:GeorgiaPowerMember2021-01-012021-01-010000092122so:GeorgiaPowerMembersrt:MinimumMember2019-12-310000092122so:GeorgiaPowerMembersrt:MaximumMember2019-12-310000092122so:GeorgiaPowerMember2018-01-012018-12-310000092122so:GeorgiaPowerMember2013-12-310000092122so:GeorgiaPowerMembersrt:MinimumMember2013-12-310000092122so:GeorgiaPowerMembersrt:MaximumMember2013-12-310000092122so:GeorgiaPowerMemberso:CustomerRefundsMember2019-12-310000092122so:GeorgiaPowerMemberso:PlantVogtleUnit3Member2021-11-022021-11-020000092122so:GeorgiaPowerMemberso:PlantVogtleUnit3Member2021-06-152021-06-150000092122so:GeorgiaPowerMemberus-gaap:SubsequentEventMemberso:PlantVogtleUnit3Member2022-01-012022-01-010000092122so:GeorgiaPowerMemberus-gaap:SubsequentEventMemberso:PlantWansleyUnits1And2Member2022-01-312022-01-310000092122so:GeorgiaPowerMemberus-gaap:SubsequentEventMemberso:PlantWansleyUnits1And2Member2022-01-310000092122so:GeorgiaPowerMemberus-gaap:SubsequentEventMemberso:PlantBowenUnits1And2Member2022-01-312022-01-310000092122so:GeorgiaPowerMemberus-gaap:SubsequentEventMemberso:PlantSchererUnit3Member2022-01-312022-01-310000092122so:GeorgiaPowerMemberus-gaap:SubsequentEventMemberso:PlantSchererUnit3Member2022-01-310000092122so:GeorgiaPowerMemberso:PlantGastonUnits1Through4Memberus-gaap:SubsequentEventMember2022-01-312022-01-310000092122so:GeorgiaPowerMemberso:PlantGastonUnits1Through4Memberus-gaap:SubsequentEventMember2022-01-310000092122so:GeorgiaPowerMemberso:PlantWansleyUnits1And2Member2021-12-310000092122so:GeorgiaPowerMemberso:PlantBowenUnits1And2Member2021-12-310000092122so:GeorgiaPowerMemberso:PlantSchererUnit3Member2021-12-310000092122so:GeorgiaPowerMemberus-gaap:SubsequentEventMemberso:PlantBowenUnits3And4Member2022-01-312022-01-310000092122so:GeorgiaPowerMemberus-gaap:SubsequentEventMemberso:PlantSchererUnits1And2Member2022-01-312022-01-310000092122so:GeorgiaPowerMemberus-gaap:SubsequentEventMemberso:PlantSchererUnits1And2Member2022-01-310000092122so:GeorgiaPowerMemberus-gaap:SubsequentEventMemberso:PlantSinclairMember2022-01-312022-01-310000092122so:GeorgiaPowerMemberus-gaap:SubsequentEventMemberso:PlantNorthHighlandsMember2022-01-312022-01-310000092122so:GeorgiaPowerMemberus-gaap:SubsequentEventMemberso:PlantBurtonMember2022-01-312022-01-310000092122so:GeorgiaPowerMemberus-gaap:SubsequentEventMembersrt:ScenarioForecastMember2029-01-012029-12-310000092122so:GeorgiaPowerMemberus-gaap:SubsequentEventMember2035-01-012035-12-310000092122so:GeorgiaPowerMemberus-gaap:SubsequentEventMembersrt:ScenarioForecastMember2030-01-012030-12-310000092122so:GeorgiaPowerMemberus-gaap:SubsequentEventMembersrt:ScenarioForecastMember2026-01-012026-12-310000092122so:GeorgiaPowerMemberus-gaap:SubsequentEventMember2022-01-312022-01-310000092122so:GeorgiaPowerMemberus-gaap:SubsequentEventMembersrt:ScenarioForecastMember2024-01-012024-01-010000092122so:GeorgiaPowerMemberus-gaap:SubsequentEventMembersrt:ScenarioForecastMember2025-01-012025-12-310000092122so:GeorgiaPowerMemberus-gaap:SubsequentEventMembersrt:ScenarioForecastMember2028-01-012028-12-310000092122so:GeorgiaPowerMemberus-gaap:SubsequentEventMembersrt:ScenarioForecastMember2024-01-012024-12-310000092122so:GeorgiaPowerMember2020-05-310000092122so:GeorgiaPowerMember2020-05-012020-05-310000092122so:GeorgiaPowerMember2020-06-012020-09-300000092122so:GeorgiaPowerMember2021-11-182021-11-180000092122so:GeorgiaPowerMemberso:StormReserveMember2021-12-310000092122so:GeorgiaPowerMemberso:StormReserveMember2020-12-310000092122so:GeorgiaPowerMemberso:StormAndPropertyDamageReservesLiabilityMember2021-12-310000092122so:GeorgiaPowerMemberso:StormAndPropertyDamageReservesLiabilityMember2020-12-310000092122so:GeorgiaPowerMember2013-01-012013-12-310000092122so:GeorgiaPowerMemberso:PlantVogtleUnits3And4Member2021-12-310000092122so:GeorgiaPowerMember2012-01-012012-12-31so:utility0000092122so:GeorgiaPowerMemberso:VogtleOwnersMemberso:PlantVogtleUnits3And4Member2021-01-012021-12-310000092122so:GeorgiaPowerMember2021-10-012021-12-310000092122so:GeorgiaPowerMemberso:PlantVogtleUnits3And4Member2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:PlantVogtleUnits3And4Memberso:TwentyFifthVogtleConstructionMonitoringReportMember2021-06-300000092122so:GeorgiaPowerMemberso:PlantVogtleUnits3And4Memberso:TwentyFifthVogtleConstructionMonitoringReportMember2021-01-012021-06-300000092122so:GeorgiaPowerMembersrt:MinimumMemberso:COVID19Memberso:PlantVogtleUnits3And4Member2021-01-012021-12-310000092122so:GeorgiaPowerMembersrt:MaximumMemberso:COVID19Memberso:PlantVogtleUnits3And4Member2021-01-012021-12-310000092122so:GeorgiaPowerMembersrt:MinimumMemberso:COVID19Memberso:PlantVogtleUnits3And4Member2021-12-310000092122so:GeorgiaPowerMembersrt:MaximumMemberso:COVID19Memberso:PlantVogtleUnits3And4Member2021-12-310000092122so:GeorgiaPowerMember2021-01-012021-03-310000092122so:GeorgiaPowerMember2021-04-012021-06-300000092122so:GeorgiaPowerMember2021-07-012021-09-300000092122so:GeorgiaPowerMemberso:PlantVogtleUnit3Member2021-01-012021-12-310000092122so:PlantWatsonUnit4Memberso:GeorgiaPowerMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:CategoryIMemberso:PlantVogtleUnits3And4Member2021-12-310000092122so:GeorgiaPowerMemberso:CategoryIMemberso:PlantVogtleUnits3And4Member2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:CategoryIIMemberso:PlantVogtleUnits3And4Member2021-01-012021-12-310000092122so:GeorgiaPowerMembersrt:MinimumMemberso:CategoryIIMemberso:PlantVogtleUnits3And4Member2021-01-012021-12-310000092122so:GeorgiaPowerMembersrt:MaximumMemberso:CategoryIIMemberso:PlantVogtleUnits3And4Member2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:VogtleOwnersMemberso:CategoryIIMemberso:PlantVogtleUnits3And4Member2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:CategoryIIIMemberso:PlantVogtleUnits3And4Member2021-01-012021-12-310000092122so:GeorgiaPowerMembersrt:MaximumMemberso:CategoryIIIMemberso:PlantVogtleUnits3And4Member2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:VogtleOwnersMemberso:CategoryIIIMemberso:PlantVogtleUnits3And4Member2021-01-012021-12-310000092122so:GeorgiaPowerMember2019-03-012019-03-310000092122so:GeorgiaPowerMembersrt:MinimumMemberso:PlantVogtleUnits3And4Member2021-01-012021-12-310000092122so:GeorgiaPowerMembersrt:MaximumMemberso:PlantVogtleUnits3And4Member2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:PlantVogtleUnits3And4Member2009-01-012009-12-310000092122so:GeorgiaPowerMemberso:PlantVogtleUnits3And4Member2018-01-110000092122so:GeorgiaPowerMemberso:PlantVogtleUnits3And4Member2021-11-182021-11-180000092122so:GeorgiaPowerMemberso:PlantVogtleUnits3And4Member2015-01-012015-12-310000092122so:GeorgiaPowerMemberso:PlantVogtleUnits3And4Member2018-01-112018-01-110000092122so:GeorgiaPowerMemberso:PlantVogtleUnits3And4Member2015-12-310000092122so:GeorgiaPowerMemberso:PlantVogtleUnits3And4Member2016-01-012016-01-010000092122so:GeorgiaPowerMemberso:PlantVogtleUnits3And4Member2020-01-012020-01-010000092122so:GeorgiaPowerMemberso:PlantVogtleUnits3And4Member2021-01-012021-01-010000092122so:GeorgiaPowerMemberso:PlantVogtleUnits3And4Member2018-01-012018-01-010000092122so:GeorgiaPowerMemberso:PlantVogtleUnits3And4Member2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:PlantVogtleUnits3And4Member2019-01-012019-12-310000092122so:GeorgiaPowerMembersrt:ScenarioForecastMemberso:PlantVogtleUnits3And4Member2022-01-012022-12-310000092122so:GeorgiaPowerMembersrt:ScenarioForecastMemberso:PlantVogtleUnits3And4Member2023-01-012023-12-31so:report0000092122so:GeorgiaPowerMemberso:PlantVogtleUnits3And4Member2018-06-300000092122so:MississippiPowerMember2020-03-012020-03-310000092122so:MississippiPowerMember2020-03-310000092122srt:WeightedAverageMemberso:MississippiPowerMemberso:MeasurementInputAverageCustomerPriceMember2021-12-310000092122srt:WeightedAverageMemberso:MississippiPowerMemberso:MeasurementInputServiceReliabilityMember2021-12-310000092122srt:WeightedAverageMemberso:MississippiPowerMemberso:MeasurementInputCustomerSatisfactionMember2021-12-31so:filing0000092122so:MississippiPowerMember2021-06-082021-06-080000092122so:PlantWatsonUnit4Memberso:MississippiPowerMember2021-09-090000092122so:AlabamaPowerMemberso:PlantGreeneCountyUnits1And2Memberso:MississippiPowerMember2021-09-090000092122so:MississippiPowerMemberso:PlantDanielUnits1And2Member2021-09-090000092122so:MississippiPowerMemberso:PlantDanielUnits1And2Member2021-12-310000092122so:EnvironmentalComplianceOverviewPlanMemberso:MississippiPowerMember2019-12-310000092122so:EnvironmentalComplianceOverviewPlanMemberso:MississippiPowerAndGulfPowerMember2019-12-310000092122so:EnvironmentalComplianceOverviewPlanMemberso:MississippiPowerMemberus-gaap:PropertyPlantAndEquipmentMember2021-12-310000092122so:EnvironmentalComplianceOverviewPlanMemberso:MississippiPowerMemberus-gaap:ConstructionInProgressMember2021-12-310000092122so:EnvironmentalComplianceOverviewPlanMemberso:MississippiPowerMemberso:AshPondMember2021-12-310000092122so:EnvironmentalComplianceOverviewPlanMemberso:MississippiPowerMember2021-06-082021-06-080000092122so:MississippiPowerMemberus-gaap:RetailMember2019-02-012019-02-280000092122so:MississippiPowerMemberus-gaap:RetailMember2020-02-012020-02-290000092122so:MississippiPowerMemberus-gaap:RetailMember2021-02-012021-02-280000092122srt:ScenarioForecastMemberso:MississippiPowerMemberus-gaap:RetailMember2022-02-012022-02-280000092122so:MississippiPowerMemberus-gaap:RetailMember2021-12-310000092122so:MississippiPowerMemberus-gaap:RetailMember2020-12-310000092122so:MississippiPowerMemberso:MraRevenueMember2020-01-012020-01-310000092122so:MississippiPowerMemberso:MraRevenueMember2021-01-012021-01-310000092122us-gaap:SubsequentEventMemberso:MississippiPowerMemberso:MraRevenueMember2022-01-012022-01-310000092122so:MississippiPowerMemberso:MraRevenueMember2020-12-310000092122so:MississippiPowerMember2021-04-062021-04-060000092122so:MississippiPowerMemberus-gaap:RetailMember2020-12-310000092122so:HurricanesZetaAndIdaAccountingOrderMemberso:MississippiPowerMember2021-10-140000092122so:MississippiPowerMemberus-gaap:RetailMember2021-12-310000092122so:MississippiPowerMember2021-12-072021-12-0700000921222021-12-072021-12-070000092122so:MississippiPowerMember2021-12-070000092122so:MississippiPowerMemberso:CooperativeEnergyMember2021-01-012021-12-310000092122so:MississippiPowerMemberso:CooperativeEnergyMember2020-12-310000092122so:MississippiPowerMember2020-06-252020-06-250000092122so:NicorGasMember2021-01-012021-12-310000092122so:AtlantaGasLightMember2021-01-012021-12-310000092122so:VirginiaNaturalGasMember2021-01-012021-12-310000092122so:ChattanoogaGasMember2021-01-012021-12-310000092122so:GasDistributionOperationsMemberso:SouthernCompanyGasMemberus-gaap:OperatingSegmentsMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberso:InvestingInIllinoisMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberso:InvestingInIllinoisMember2021-12-31utr:mi0000092122so:SouthernCompanyGasMemberso:SAVEMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberso:SAVEMember2021-12-310000092122so:SystemReinforcementRiderMemberso:SouthernCompanyGasMember2021-01-012021-12-310000092122so:SystemReinforcementRiderMemberso:SouthernCompanyGasMember2021-12-310000092122so:SouthernCompanyGasMemberso:PipelineReplacementProgramMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberso:PipelineReplacementProgramMember2021-12-310000092122srt:MaximumMemberso:NicorGasMember2014-01-012014-12-310000092122so:RegulatoryInfrastructureProgramMemberso:NicorGasMember2014-01-012014-12-310000092122so:NicorGasMember2020-01-012020-12-310000092122so:NicorGasMember2019-01-012019-12-310000092122so:Year2018Memberso:VirginiaNaturalGasMemberso:SAVEMember2019-12-310000092122so:VirginiaNaturalGasMemberso:Year2019Memberso:SAVEMember2019-12-310000092122so:Year2020Memberso:VirginiaNaturalGasMemberso:SAVEMember2019-12-310000092122so:VirginiaNaturalGasMemberso:Year2021Memberso:SAVEMember2019-12-310000092122so:Year2023Memberso:VirginiaNaturalGasMemberso:SAVEMember2019-12-310000092122so:Year2022Memberso:VirginiaNaturalGasMemberso:SAVEMember2019-12-310000092122so:Year2024Memberso:VirginiaNaturalGasMemberso:SAVEMember2019-12-310000092122so:VirginiaNaturalGasMemberso:SAVEMember2019-12-310000092122so:VirginiaNaturalGasMemberso:SAVEMember2019-01-012019-12-310000092122so:SouthernCompanyGasMemberso:SAVEMember2020-01-012020-12-310000092122so:SouthernCompanyGasMemberso:SAVEMember2019-01-012019-12-310000092122so:TrueUpRecoveryUnrecognizedEquityMemberso:AtlantaGasLightMember2021-12-310000092122so:AtlantaGasLightMember2021-11-182021-11-180000092122so:ChattanoogaGasMember2021-06-012021-06-300000092122so:ChattanoogaGasMember2021-06-300000092122so:SouthernCompanyGasMemberso:NaturalGasCostUnderRecoveryMember2021-12-310000092122so:SouthernCompanyGasMemberso:OtherRegulatoryAssetsDeferredMember2021-12-310000092122so:InvestingInIllinoisMemberso:NicorGasMember2019-01-012019-12-310000092122so:NicorGasMember2021-11-182021-11-180000092122so:InvestingInIllinoisMemberso:NicorGasMember2021-11-182021-11-180000092122so:AtlantaGasLightMember2019-12-012019-12-310000092122srt:MinimumMemberso:AtlantaGasLightMember2019-12-012019-12-310000092122srt:MaximumMemberso:AtlantaGasLightMember2019-12-012019-12-310000092122so:AtlantaGasLightMember2020-07-012020-07-010000092122so:AtlantaGasLightMember2020-07-310000092122so:AtlantaGasLightMember2021-02-162021-02-160000092122so:AtlantaGasLightMember2021-04-282021-04-280000092122srt:MinimumMemberso:AtlantaGasLightMember2021-04-280000092122srt:MaximumMemberso:AtlantaGasLightMember2021-04-280000092122so:AtlantaGasLightMember2021-11-180000092122us-gaap:SubsequentEventMemberso:AtlantaGasLightMember2022-01-012022-01-010000092122so:VirginiaNaturalGasMember2021-09-142021-09-140000092122so:VirginiaNaturalGasMember2020-11-012020-11-010000092122so:NicorGasMemberso:COVID19Member2021-12-310000092122so:NicorGasMemberso:COVID19Member2020-12-310000092122so:AtlantaGasLightMemberso:RegulatoryAssetOffBalanceSheetMember2021-12-310000092122so:AtlantaGasLightMemberso:RegulatoryAssetOffBalanceSheetMember2020-12-310000092122so:VirginiaNaturalGasMemberso:RegulatoryAssetOffBalanceSheetMember2021-12-310000092122so:VirginiaNaturalGasMemberso:RegulatoryAssetOffBalanceSheetMember2020-12-310000092122so:RegulatoryAssetOffBalanceSheetMemberso:ChattanoogaGasMember2021-12-310000092122so:RegulatoryAssetOffBalanceSheetMemberso:ChattanoogaGasMember2020-12-310000092122so:RegulatoryAssetOffBalanceSheetMemberso:NicorGasMember2021-12-310000092122so:RegulatoryAssetOffBalanceSheetMemberso:NicorGasMember2020-12-310000092122so:SouthernCompanyGasMemberso:RegulatoryAssetOffBalanceSheetMember2021-12-310000092122so:SouthernCompanyGasMemberso:RegulatoryAssetOffBalanceSheetMember2020-12-310000092122so:ShareholderDerivativeLawsuitsMemberus-gaap:PendingLitigationMember2017-12-31so:lawsuit0000092122so:GeorgiaPowerMemberus-gaap:PendingLitigationMemberso:ClassActionLawsuitMember2020-10-082020-10-08so:claim0000092122so:GeorgiaPowerMemberus-gaap:SubsequentEventMemberus-gaap:PendingLitigationMemberso:ClassActionLawsuitMember2022-02-072022-02-070000092122us-gaap:PendingLitigationMemberso:MississippiPowerMemberso:PurportedViolationsOfMississippiConsumerProtectionActMember2018-01-012018-12-31so:plaintiffso:defendant0000092122us-gaap:PendingLitigationMemberso:MississippiPowerMemberso:PurportedViolationsOfMississippiConsumerProtectionActMember2019-03-012019-03-310000092122so:SouthernCompanyGasMemberso:ManufacturedGasPlantsMember2021-12-31so:site0000092122so:SouthernCompanyMember2021-12-310000092122so:SouthernCompanyMember2020-12-310000092122us-gaap:PositiveOutcomeOfLitigationMemberso:AlabamaPowerMember2011-01-012019-12-310000092122so:GeorgiaPowerMemberus-gaap:PositiveOutcomeOfLitigationMember2011-01-012019-12-310000092122so:AlabamaPowerAndGeorgiaPowerMember2021-12-31so:plant0000092122so:AlabamaPowerAndGeorgiaPowerMember2021-01-012021-12-310000092122so:VogtleUnitsThreeAndFourMember2021-01-012021-12-310000092122so:KemperIgccMemberso:MississippiPowerMember2019-01-012019-12-310000092122so:KemperIgccMemberso:MississippiPowerMember2020-01-012020-12-310000092122so:KemperIgccMemberso:MississippiPowerMember2021-01-012021-12-310000092122srt:ScenarioForecastMemberso:KemperIgccMemberso:MississippiPowerMembersrt:MinimumMember2021-01-012025-12-310000092122srt:ScenarioForecastMemberso:KemperIgccMembersrt:MaximumMemberso:MississippiPowerMember2021-01-012025-12-310000092122so:KemperIgccMemberso:MississippiPowerMember2010-12-310000092122so:KemperIgccMemberso:MississippiPowerMember2016-12-310000092122so:KemperIgccMemberso:MississippiPowerMember2018-01-012018-12-310000092122us-gaap:DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMemberso:GulfPowerMember2019-01-012019-01-010000092122srt:ScenarioForecastMemberso:PlantDanielUnits1And2Memberso:GulfPowerMember2019-01-152024-01-150000092122srt:ScenarioForecastMemberso:MississippiPowerMemberso:PlantDanielUnits1And2Member2019-01-152024-01-150000092122so:GeorgiaPowerMemberso:MeagPowerMember2021-12-310000092122so:GeorgiaPowerMemberso:PlantVogtleNuclearUnitsOneAndTwoMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:PlantVogtleNuclearUnitsOneAndTwoMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:PlantVogtleNuclearUnitsOneAndTwoMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:PlantVogtleNuclearUnitsOneAndTwoMember2021-12-31utr:MMBTU0000092122so:SouthernCompanyGasMemberso:PipelineChargesStorageCapacityAndGasSupplyMember2021-12-310000092122so:AlabamaPowerMemberso:SouthernElectricGeneratingCompanyMember2021-12-310000092122so:RetailElectricResidentialMember2021-01-012021-12-310000092122so:RetailElectricResidentialMemberso:AlabamaPowerMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:RetailElectricResidentialMember2021-01-012021-12-310000092122so:RetailElectricResidentialMemberso:MississippiPowerMember2021-01-012021-12-310000092122so:RetailElectricResidentialMemberso:SouthernPowerMember2021-01-012021-12-310000092122so:RetailElectricResidentialMemberso:SouthernCompanyGasMember2021-01-012021-12-310000092122so:RetailElectricCommercialMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:RetailElectricCommercialMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:RetailElectricCommercialMember2021-01-012021-12-310000092122so:MississippiPowerMemberso:RetailElectricCommercialMember2021-01-012021-12-310000092122so:SouthernPowerMemberso:RetailElectricCommercialMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberso:RetailElectricCommercialMember2021-01-012021-12-310000092122so:RetailElectricIndustrialMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:RetailElectricIndustrialMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:RetailElectricIndustrialMember2021-01-012021-12-310000092122so:RetailElectricIndustrialMemberso:MississippiPowerMember2021-01-012021-12-310000092122so:RetailElectricIndustrialMemberso:SouthernPowerMember2021-01-012021-12-310000092122so:RetailElectricIndustrialMemberso:SouthernCompanyGasMember2021-01-012021-12-310000092122so:RetailElectricOtherMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:RetailElectricOtherMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:RetailElectricOtherMember2021-01-012021-12-310000092122so:RetailElectricOtherMemberso:MississippiPowerMember2021-01-012021-12-310000092122so:RetailElectricOtherMemberso:SouthernPowerMember2021-01-012021-12-310000092122so:RetailElectricOtherMemberso:SouthernCompanyGasMember2021-01-012021-12-310000092122so:RetailElectricMember2021-01-012021-12-310000092122so:RetailElectricMemberso:AlabamaPowerMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:RetailElectricMember2021-01-012021-12-310000092122so:RetailElectricMemberso:MississippiPowerMember2021-01-012021-12-310000092122so:RetailElectricMemberso:SouthernPowerMember2021-01-012021-12-310000092122so:RetailElectricMemberso:SouthernCompanyGasMember2021-01-012021-12-310000092122so:NaturalGasDistributionResidentialMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:NaturalGasDistributionResidentialMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:NaturalGasDistributionResidentialMember2021-01-012021-12-310000092122so:MississippiPowerMemberso:NaturalGasDistributionResidentialMember2021-01-012021-12-310000092122so:NaturalGasDistributionResidentialMemberso:SouthernPowerMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberso:NaturalGasDistributionResidentialMember2021-01-012021-12-310000092122so:NaturalGasDistributionCommercialMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:NaturalGasDistributionCommercialMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:NaturalGasDistributionCommercialMember2021-01-012021-12-310000092122so:MississippiPowerMemberso:NaturalGasDistributionCommercialMember2021-01-012021-12-310000092122so:NaturalGasDistributionCommercialMemberso:SouthernPowerMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberso:NaturalGasDistributionCommercialMember2021-01-012021-12-310000092122so:NaturalGasDistributionTransportationMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:NaturalGasDistributionTransportationMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:NaturalGasDistributionTransportationMember2021-01-012021-12-310000092122so:MississippiPowerMemberso:NaturalGasDistributionTransportationMember2021-01-012021-12-310000092122so:SouthernPowerMemberso:NaturalGasDistributionTransportationMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberso:NaturalGasDistributionTransportationMember2021-01-012021-12-310000092122so:NaturalGasDistributionIndustrialMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:NaturalGasDistributionIndustrialMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:NaturalGasDistributionIndustrialMember2021-01-012021-12-310000092122so:MississippiPowerMemberso:NaturalGasDistributionIndustrialMember2021-01-012021-12-310000092122so:NaturalGasDistributionIndustrialMemberso:SouthernPowerMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberso:NaturalGasDistributionIndustrialMember2021-01-012021-12-310000092122so:NaturalGasDistributionOtherMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:NaturalGasDistributionOtherMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:NaturalGasDistributionOtherMember2021-01-012021-12-310000092122so:MississippiPowerMemberso:NaturalGasDistributionOtherMember2021-01-012021-12-310000092122so:NaturalGasDistributionOtherMemberso:SouthernPowerMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberso:NaturalGasDistributionOtherMember2021-01-012021-12-310000092122so:NaturalGasDistributionMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:NaturalGasDistributionMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:NaturalGasDistributionMember2021-01-012021-12-310000092122so:MississippiPowerMemberso:NaturalGasDistributionMember2021-01-012021-12-310000092122so:SouthernPowerMemberso:NaturalGasDistributionMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberso:NaturalGasDistributionMember2021-01-012021-12-310000092122so:WholesaleElectricPPAEnergyRevenuesMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:WholesaleElectricPPAEnergyRevenuesMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:WholesaleElectricPPAEnergyRevenuesMember2021-01-012021-12-310000092122so:MississippiPowerMemberso:WholesaleElectricPPAEnergyRevenuesMember2021-01-012021-12-310000092122so:WholesaleElectricPPAEnergyRevenuesMemberso:SouthernPowerMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberso:WholesaleElectricPPAEnergyRevenuesMember2021-01-012021-12-310000092122so:WholesaleElectricPPACapacityRevenuesMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:WholesaleElectricPPACapacityRevenuesMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:WholesaleElectricPPACapacityRevenuesMember2021-01-012021-12-310000092122so:MississippiPowerMemberso:WholesaleElectricPPACapacityRevenuesMember2021-01-012021-12-310000092122so:WholesaleElectricPPACapacityRevenuesMemberso:SouthernPowerMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberso:WholesaleElectricPPACapacityRevenuesMember2021-01-012021-12-310000092122so:WholesaleElectricNonPPARevenuesMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:WholesaleElectricNonPPARevenuesMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:WholesaleElectricNonPPARevenuesMember2021-01-012021-12-310000092122so:WholesaleElectricNonPPARevenuesMemberso:MississippiPowerMember2021-01-012021-12-310000092122so:WholesaleElectricNonPPARevenuesMemberso:SouthernPowerMember2021-01-012021-12-310000092122so:WholesaleElectricNonPPARevenuesMemberso:SouthernCompanyGasMember2021-01-012021-12-310000092122so:WholesaleElectricRevenuesMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:WholesaleElectricRevenuesMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:WholesaleElectricRevenuesMember2021-01-012021-12-310000092122so:MississippiPowerMemberso:WholesaleElectricRevenuesMember2021-01-012021-12-310000092122so:WholesaleElectricRevenuesMemberso:SouthernPowerMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberso:WholesaleElectricRevenuesMember2021-01-012021-12-310000092122so:OtherNaturalGasWholesaleGasServicesMember2021-01-012021-12-310000092122so:OtherNaturalGasWholesaleGasServicesMemberso:AlabamaPowerMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:OtherNaturalGasWholesaleGasServicesMember2021-01-012021-12-310000092122so:OtherNaturalGasWholesaleGasServicesMemberso:MississippiPowerMember2021-01-012021-12-310000092122so:OtherNaturalGasWholesaleGasServicesMemberso:SouthernPowerMember2021-01-012021-12-310000092122so:OtherNaturalGasWholesaleGasServicesMemberso:SouthernCompanyGasMember2021-01-012021-12-310000092122so:OtherNaturalGasGasMarketingServicesMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:OtherNaturalGasGasMarketingServicesMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:OtherNaturalGasGasMarketingServicesMember2021-01-012021-12-310000092122so:MississippiPowerMemberso:OtherNaturalGasGasMarketingServicesMember2021-01-012021-12-310000092122so:SouthernPowerMemberso:OtherNaturalGasGasMarketingServicesMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberso:OtherNaturalGasGasMarketingServicesMember2021-01-012021-12-310000092122so:OtherNaturalGasOtherNaturalGasRevenuesMember2021-01-012021-12-310000092122so:OtherNaturalGasOtherNaturalGasRevenuesMemberso:AlabamaPowerMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:OtherNaturalGasOtherNaturalGasRevenuesMember2021-01-012021-12-310000092122so:OtherNaturalGasOtherNaturalGasRevenuesMemberso:MississippiPowerMember2021-01-012021-12-310000092122so:OtherNaturalGasOtherNaturalGasRevenuesMemberso:SouthernPowerMember2021-01-012021-12-310000092122so:OtherNaturalGasOtherNaturalGasRevenuesMemberso:SouthernCompanyGasMember2021-01-012021-12-310000092122so:OtherNaturalGasMember2021-01-012021-12-310000092122so:OtherNaturalGasMemberso:AlabamaPowerMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:OtherNaturalGasMember2021-01-012021-12-310000092122so:OtherNaturalGasMemberso:MississippiPowerMember2021-01-012021-12-310000092122so:OtherNaturalGasMemberso:SouthernPowerMember2021-01-012021-12-310000092122so:OtherNaturalGasMemberso:SouthernCompanyGasMember2021-01-012021-12-310000092122so:OtherRevenuesMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:OtherRevenuesMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:OtherRevenuesMember2021-01-012021-12-310000092122so:MississippiPowerMemberso:OtherRevenuesMember2021-01-012021-12-310000092122so:SouthernPowerMemberso:OtherRevenuesMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberso:OtherRevenuesMember2021-01-012021-12-310000092122so:OtherRevenueSourcesMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:OtherRevenueSourcesMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:OtherRevenueSourcesMember2021-01-012021-12-310000092122so:MississippiPowerMemberso:OtherRevenueSourcesMember2021-01-012021-12-310000092122so:SouthernPowerMemberso:OtherRevenueSourcesMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberso:OtherRevenueSourcesMember2021-01-012021-12-310000092122so:OtherAdjustmentsMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:OtherAdjustmentsMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:OtherAdjustmentsMember2021-01-012021-12-310000092122so:MississippiPowerMemberso:OtherAdjustmentsMember2021-01-012021-12-310000092122so:SouthernPowerMemberso:OtherAdjustmentsMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberso:OtherAdjustmentsMember2021-01-012021-12-310000092122so:RetailElectricResidentialMember2020-01-012020-12-310000092122so:RetailElectricResidentialMemberso:AlabamaPowerMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:RetailElectricResidentialMember2020-01-012020-12-310000092122so:RetailElectricResidentialMemberso:MississippiPowerMember2020-01-012020-12-310000092122so:RetailElectricResidentialMemberso:SouthernPowerMember2020-01-012020-12-310000092122so:RetailElectricResidentialMemberso:SouthernCompanyGasMember2020-01-012020-12-310000092122so:RetailElectricCommercialMember2020-01-012020-12-310000092122so:AlabamaPowerMemberso:RetailElectricCommercialMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:RetailElectricCommercialMember2020-01-012020-12-310000092122so:MississippiPowerMemberso:RetailElectricCommercialMember2020-01-012020-12-310000092122so:SouthernPowerMemberso:RetailElectricCommercialMember2020-01-012020-12-310000092122so:SouthernCompanyGasMemberso:RetailElectricCommercialMember2020-01-012020-12-310000092122so:RetailElectricIndustrialMember2020-01-012020-12-310000092122so:AlabamaPowerMemberso:RetailElectricIndustrialMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:RetailElectricIndustrialMember2020-01-012020-12-310000092122so:RetailElectricIndustrialMemberso:MississippiPowerMember2020-01-012020-12-310000092122so:RetailElectricIndustrialMemberso:SouthernPowerMember2020-01-012020-12-310000092122so:RetailElectricIndustrialMemberso:SouthernCompanyGasMember2020-01-012020-12-310000092122so:RetailElectricOtherMember2020-01-012020-12-310000092122so:AlabamaPowerMemberso:RetailElectricOtherMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:RetailElectricOtherMember2020-01-012020-12-310000092122so:RetailElectricOtherMemberso:MississippiPowerMember2020-01-012020-12-310000092122so:RetailElectricOtherMemberso:SouthernPowerMember2020-01-012020-12-310000092122so:RetailElectricOtherMemberso:SouthernCompanyGasMember2020-01-012020-12-310000092122so:RetailElectricMember2020-01-012020-12-310000092122so:RetailElectricMemberso:AlabamaPowerMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:RetailElectricMember2020-01-012020-12-310000092122so:RetailElectricMemberso:MississippiPowerMember2020-01-012020-12-310000092122so:RetailElectricMemberso:SouthernPowerMember2020-01-012020-12-310000092122so:RetailElectricMemberso:SouthernCompanyGasMember2020-01-012020-12-310000092122so:NaturalGasDistributionResidentialMember2020-01-012020-12-310000092122so:AlabamaPowerMemberso:NaturalGasDistributionResidentialMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:NaturalGasDistributionResidentialMember2020-01-012020-12-310000092122so:MississippiPowerMemberso:NaturalGasDistributionResidentialMember2020-01-012020-12-310000092122so:NaturalGasDistributionResidentialMemberso:SouthernPowerMember2020-01-012020-12-310000092122so:SouthernCompanyGasMemberso:NaturalGasDistributionResidentialMember2020-01-012020-12-310000092122so:NaturalGasDistributionCommercialMember2020-01-012020-12-310000092122so:AlabamaPowerMemberso:NaturalGasDistributionCommercialMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:NaturalGasDistributionCommercialMember2020-01-012020-12-310000092122so:MississippiPowerMemberso:NaturalGasDistributionCommercialMember2020-01-012020-12-310000092122so:NaturalGasDistributionCommercialMemberso:SouthernPowerMember2020-01-012020-12-310000092122so:SouthernCompanyGasMemberso:NaturalGasDistributionCommercialMember2020-01-012020-12-310000092122so:NaturalGasDistributionTransportationMember2020-01-012020-12-310000092122so:AlabamaPowerMemberso:NaturalGasDistributionTransportationMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:NaturalGasDistributionTransportationMember2020-01-012020-12-310000092122so:MississippiPowerMemberso:NaturalGasDistributionTransportationMember2020-01-012020-12-310000092122so:SouthernPowerMemberso:NaturalGasDistributionTransportationMember2020-01-012020-12-310000092122so:SouthernCompanyGasMemberso:NaturalGasDistributionTransportationMember2020-01-012020-12-310000092122so:NaturalGasDistributionIndustrialMember2020-01-012020-12-310000092122so:AlabamaPowerMemberso:NaturalGasDistributionIndustrialMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:NaturalGasDistributionIndustrialMember2020-01-012020-12-310000092122so:MississippiPowerMemberso:NaturalGasDistributionIndustrialMember2020-01-012020-12-310000092122so:NaturalGasDistributionIndustrialMemberso:SouthernPowerMember2020-01-012020-12-310000092122so:SouthernCompanyGasMemberso:NaturalGasDistributionIndustrialMember2020-01-012020-12-310000092122so:NaturalGasDistributionOtherMember2020-01-012020-12-310000092122so:AlabamaPowerMemberso:NaturalGasDistributionOtherMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:NaturalGasDistributionOtherMember2020-01-012020-12-310000092122so:MississippiPowerMemberso:NaturalGasDistributionOtherMember2020-01-012020-12-310000092122so:NaturalGasDistributionOtherMemberso:SouthernPowerMember2020-01-012020-12-310000092122so:SouthernCompanyGasMemberso:NaturalGasDistributionOtherMember2020-01-012020-12-310000092122so:NaturalGasDistributionMember2020-01-012020-12-310000092122so:AlabamaPowerMemberso:NaturalGasDistributionMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:NaturalGasDistributionMember2020-01-012020-12-310000092122so:MississippiPowerMemberso:NaturalGasDistributionMember2020-01-012020-12-310000092122so:SouthernPowerMemberso:NaturalGasDistributionMember2020-01-012020-12-310000092122so:SouthernCompanyGasMemberso:NaturalGasDistributionMember2020-01-012020-12-310000092122so:WholesaleElectricPPAEnergyRevenuesMember2020-01-012020-12-310000092122so:AlabamaPowerMemberso:WholesaleElectricPPAEnergyRevenuesMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:WholesaleElectricPPAEnergyRevenuesMember2020-01-012020-12-310000092122so:MississippiPowerMemberso:WholesaleElectricPPAEnergyRevenuesMember2020-01-012020-12-310000092122so:WholesaleElectricPPAEnergyRevenuesMemberso:SouthernPowerMember2020-01-012020-12-310000092122so:SouthernCompanyGasMemberso:WholesaleElectricPPAEnergyRevenuesMember2020-01-012020-12-310000092122so:WholesaleElectricPPACapacityRevenuesMember2020-01-012020-12-310000092122so:AlabamaPowerMemberso:WholesaleElectricPPACapacityRevenuesMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:WholesaleElectricPPACapacityRevenuesMember2020-01-012020-12-310000092122so:MississippiPowerMemberso:WholesaleElectricPPACapacityRevenuesMember2020-01-012020-12-310000092122so:WholesaleElectricPPACapacityRevenuesMemberso:SouthernPowerMember2020-01-012020-12-310000092122so:SouthernCompanyGasMemberso:WholesaleElectricPPACapacityRevenuesMember2020-01-012020-12-310000092122so:WholesaleElectricNonPPARevenuesMember2020-01-012020-12-310000092122so:AlabamaPowerMemberso:WholesaleElectricNonPPARevenuesMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:WholesaleElectricNonPPARevenuesMember2020-01-012020-12-310000092122so:WholesaleElectricNonPPARevenuesMemberso:MississippiPowerMember2020-01-012020-12-310000092122so:WholesaleElectricNonPPARevenuesMemberso:SouthernPowerMember2020-01-012020-12-310000092122so:WholesaleElectricNonPPARevenuesMemberso:SouthernCompanyGasMember2020-01-012020-12-310000092122so:WholesaleElectricRevenuesMember2020-01-012020-12-310000092122so:AlabamaPowerMemberso:WholesaleElectricRevenuesMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:WholesaleElectricRevenuesMember2020-01-012020-12-310000092122so:MississippiPowerMemberso:WholesaleElectricRevenuesMember2020-01-012020-12-310000092122so:WholesaleElectricRevenuesMemberso:SouthernPowerMember2020-01-012020-12-310000092122so:SouthernCompanyGasMemberso:WholesaleElectricRevenuesMember2020-01-012020-12-310000092122so:OtherNaturalGasWholesaleGasServicesMember2020-01-012020-12-310000092122so:OtherNaturalGasWholesaleGasServicesMemberso:AlabamaPowerMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:OtherNaturalGasWholesaleGasServicesMember2020-01-012020-12-310000092122so:OtherNaturalGasWholesaleGasServicesMemberso:MississippiPowerMember2020-01-012020-12-310000092122so:OtherNaturalGasWholesaleGasServicesMemberso:SouthernPowerMember2020-01-012020-12-310000092122so:OtherNaturalGasWholesaleGasServicesMemberso:SouthernCompanyGasMember2020-01-012020-12-310000092122so:OtherNaturalGasGasMarketingServicesMember2020-01-012020-12-310000092122so:AlabamaPowerMemberso:OtherNaturalGasGasMarketingServicesMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:OtherNaturalGasGasMarketingServicesMember2020-01-012020-12-310000092122so:MississippiPowerMemberso:OtherNaturalGasGasMarketingServicesMember2020-01-012020-12-310000092122so:SouthernPowerMemberso:OtherNaturalGasGasMarketingServicesMember2020-01-012020-12-310000092122so:SouthernCompanyGasMemberso:OtherNaturalGasGasMarketingServicesMember2020-01-012020-12-310000092122so:OtherNaturalGasOtherNaturalGasRevenuesMember2020-01-012020-12-310000092122so:OtherNaturalGasOtherNaturalGasRevenuesMemberso:AlabamaPowerMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:OtherNaturalGasOtherNaturalGasRevenuesMember2020-01-012020-12-310000092122so:OtherNaturalGasOtherNaturalGasRevenuesMemberso:MississippiPowerMember2020-01-012020-12-310000092122so:OtherNaturalGasOtherNaturalGasRevenuesMemberso:SouthernPowerMember2020-01-012020-12-310000092122so:OtherNaturalGasOtherNaturalGasRevenuesMemberso:SouthernCompanyGasMember2020-01-012020-12-310000092122so:OtherNaturalGasMember2020-01-012020-12-310000092122so:OtherNaturalGasMemberso:AlabamaPowerMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:OtherNaturalGasMember2020-01-012020-12-310000092122so:OtherNaturalGasMemberso:MississippiPowerMember2020-01-012020-12-310000092122so:OtherNaturalGasMemberso:SouthernPowerMember2020-01-012020-12-310000092122so:OtherNaturalGasMemberso:SouthernCompanyGasMember2020-01-012020-12-310000092122so:OtherRevenuesMember2020-01-012020-12-310000092122so:AlabamaPowerMemberso:OtherRevenuesMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:OtherRevenuesMember2020-01-012020-12-310000092122so:MississippiPowerMemberso:OtherRevenuesMember2020-01-012020-12-310000092122so:SouthernPowerMemberso:OtherRevenuesMember2020-01-012020-12-310000092122so:SouthernCompanyGasMemberso:OtherRevenuesMember2020-01-012020-12-310000092122so:OtherRevenueSourcesMember2020-01-012020-12-310000092122so:AlabamaPowerMemberso:OtherRevenueSourcesMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:OtherRevenueSourcesMember2020-01-012020-12-310000092122so:MississippiPowerMemberso:OtherRevenueSourcesMember2020-01-012020-12-310000092122so:SouthernPowerMemberso:OtherRevenueSourcesMember2020-01-012020-12-310000092122so:SouthernCompanyGasMemberso:OtherRevenueSourcesMember2020-01-012020-12-310000092122so:OtherAdjustmentsMember2020-01-012020-12-310000092122so:AlabamaPowerMemberso:OtherAdjustmentsMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:OtherAdjustmentsMember2020-01-012020-12-310000092122so:MississippiPowerMemberso:OtherAdjustmentsMember2020-01-012020-12-310000092122so:SouthernPowerMemberso:OtherAdjustmentsMember2020-01-012020-12-310000092122so:SouthernCompanyGasMemberso:OtherAdjustmentsMember2020-01-012020-12-310000092122so:RetailElectricResidentialMember2019-01-012019-12-310000092122so:RetailElectricResidentialMemberso:AlabamaPowerMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:RetailElectricResidentialMember2019-01-012019-12-310000092122so:RetailElectricResidentialMemberso:MississippiPowerMember2019-01-012019-12-310000092122so:RetailElectricResidentialMemberso:SouthernPowerMember2019-01-012019-12-310000092122so:RetailElectricResidentialMemberso:SouthernCompanyGasMember2019-01-012019-12-310000092122so:RetailElectricCommercialMember2019-01-012019-12-310000092122so:AlabamaPowerMemberso:RetailElectricCommercialMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:RetailElectricCommercialMember2019-01-012019-12-310000092122so:MississippiPowerMemberso:RetailElectricCommercialMember2019-01-012019-12-310000092122so:SouthernPowerMemberso:RetailElectricCommercialMember2019-01-012019-12-310000092122so:SouthernCompanyGasMemberso:RetailElectricCommercialMember2019-01-012019-12-310000092122so:RetailElectricIndustrialMember2019-01-012019-12-310000092122so:AlabamaPowerMemberso:RetailElectricIndustrialMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:RetailElectricIndustrialMember2019-01-012019-12-310000092122so:RetailElectricIndustrialMemberso:MississippiPowerMember2019-01-012019-12-310000092122so:RetailElectricIndustrialMemberso:SouthernPowerMember2019-01-012019-12-310000092122so:RetailElectricIndustrialMemberso:SouthernCompanyGasMember2019-01-012019-12-310000092122so:RetailElectricOtherMember2019-01-012019-12-310000092122so:AlabamaPowerMemberso:RetailElectricOtherMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:RetailElectricOtherMember2019-01-012019-12-310000092122so:RetailElectricOtherMemberso:MississippiPowerMember2019-01-012019-12-310000092122so:RetailElectricOtherMemberso:SouthernPowerMember2019-01-012019-12-310000092122so:RetailElectricOtherMemberso:SouthernCompanyGasMember2019-01-012019-12-310000092122so:RetailElectricMember2019-01-012019-12-310000092122so:RetailElectricMemberso:AlabamaPowerMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:RetailElectricMember2019-01-012019-12-310000092122so:RetailElectricMemberso:MississippiPowerMember2019-01-012019-12-310000092122so:RetailElectricMemberso:SouthernPowerMember2019-01-012019-12-310000092122so:RetailElectricMemberso:SouthernCompanyGasMember2019-01-012019-12-310000092122so:NaturalGasDistributionResidentialMember2019-01-012019-12-310000092122so:AlabamaPowerMemberso:NaturalGasDistributionResidentialMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:NaturalGasDistributionResidentialMember2019-01-012019-12-310000092122so:MississippiPowerMemberso:NaturalGasDistributionResidentialMember2019-01-012019-12-310000092122so:NaturalGasDistributionResidentialMemberso:SouthernPowerMember2019-01-012019-12-310000092122so:SouthernCompanyGasMemberso:NaturalGasDistributionResidentialMember2019-01-012019-12-310000092122so:NaturalGasDistributionCommercialMember2019-01-012019-12-310000092122so:AlabamaPowerMemberso:NaturalGasDistributionCommercialMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:NaturalGasDistributionCommercialMember2019-01-012019-12-310000092122so:MississippiPowerMemberso:NaturalGasDistributionCommercialMember2019-01-012019-12-310000092122so:NaturalGasDistributionCommercialMemberso:SouthernPowerMember2019-01-012019-12-310000092122so:SouthernCompanyGasMemberso:NaturalGasDistributionCommercialMember2019-01-012019-12-310000092122so:NaturalGasDistributionTransportationMember2019-01-012019-12-310000092122so:AlabamaPowerMemberso:NaturalGasDistributionTransportationMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:NaturalGasDistributionTransportationMember2019-01-012019-12-310000092122so:MississippiPowerMemberso:NaturalGasDistributionTransportationMember2019-01-012019-12-310000092122so:SouthernPowerMemberso:NaturalGasDistributionTransportationMember2019-01-012019-12-310000092122so:SouthernCompanyGasMemberso:NaturalGasDistributionTransportationMember2019-01-012019-12-310000092122so:NaturalGasDistributionIndustrialMember2019-01-012019-12-310000092122so:AlabamaPowerMemberso:NaturalGasDistributionIndustrialMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:NaturalGasDistributionIndustrialMember2019-01-012019-12-310000092122so:MississippiPowerMemberso:NaturalGasDistributionIndustrialMember2019-01-012019-12-310000092122so:NaturalGasDistributionIndustrialMemberso:SouthernPowerMember2019-01-012019-12-310000092122so:SouthernCompanyGasMemberso:NaturalGasDistributionIndustrialMember2019-01-012019-12-310000092122so:NaturalGasDistributionOtherMember2019-01-012019-12-310000092122so:AlabamaPowerMemberso:NaturalGasDistributionOtherMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:NaturalGasDistributionOtherMember2019-01-012019-12-310000092122so:MississippiPowerMemberso:NaturalGasDistributionOtherMember2019-01-012019-12-310000092122so:NaturalGasDistributionOtherMemberso:SouthernPowerMember2019-01-012019-12-310000092122so:SouthernCompanyGasMemberso:NaturalGasDistributionOtherMember2019-01-012019-12-310000092122so:NaturalGasDistributionMember2019-01-012019-12-310000092122so:AlabamaPowerMemberso:NaturalGasDistributionMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:NaturalGasDistributionMember2019-01-012019-12-310000092122so:MississippiPowerMemberso:NaturalGasDistributionMember2019-01-012019-12-310000092122so:SouthernPowerMemberso:NaturalGasDistributionMember2019-01-012019-12-310000092122so:SouthernCompanyGasMemberso:NaturalGasDistributionMember2019-01-012019-12-310000092122so:WholesaleElectricPPAEnergyRevenuesMember2019-01-012019-12-310000092122so:AlabamaPowerMemberso:WholesaleElectricPPAEnergyRevenuesMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:WholesaleElectricPPAEnergyRevenuesMember2019-01-012019-12-310000092122so:MississippiPowerMemberso:WholesaleElectricPPAEnergyRevenuesMember2019-01-012019-12-310000092122so:WholesaleElectricPPAEnergyRevenuesMemberso:SouthernPowerMember2019-01-012019-12-310000092122so:SouthernCompanyGasMemberso:WholesaleElectricPPAEnergyRevenuesMember2019-01-012019-12-310000092122so:WholesaleElectricPPACapacityRevenuesMember2019-01-012019-12-310000092122so:AlabamaPowerMemberso:WholesaleElectricPPACapacityRevenuesMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:WholesaleElectricPPACapacityRevenuesMember2019-01-012019-12-310000092122so:MississippiPowerMemberso:WholesaleElectricPPACapacityRevenuesMember2019-01-012019-12-310000092122so:WholesaleElectricPPACapacityRevenuesMemberso:SouthernPowerMember2019-01-012019-12-310000092122so:SouthernCompanyGasMemberso:WholesaleElectricPPACapacityRevenuesMember2019-01-012019-12-310000092122so:WholesaleElectricNonPPARevenuesMember2019-01-012019-12-310000092122so:AlabamaPowerMemberso:WholesaleElectricNonPPARevenuesMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:WholesaleElectricNonPPARevenuesMember2019-01-012019-12-310000092122so:WholesaleElectricNonPPARevenuesMemberso:MississippiPowerMember2019-01-012019-12-310000092122so:WholesaleElectricNonPPARevenuesMemberso:SouthernPowerMember2019-01-012019-12-310000092122so:WholesaleElectricNonPPARevenuesMemberso:SouthernCompanyGasMember2019-01-012019-12-310000092122so:WholesaleElectricRevenuesMember2019-01-012019-12-310000092122so:AlabamaPowerMemberso:WholesaleElectricRevenuesMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:WholesaleElectricRevenuesMember2019-01-012019-12-310000092122so:MississippiPowerMemberso:WholesaleElectricRevenuesMember2019-01-012019-12-310000092122so:WholesaleElectricRevenuesMemberso:SouthernPowerMember2019-01-012019-12-310000092122so:SouthernCompanyGasMemberso:WholesaleElectricRevenuesMember2019-01-012019-12-310000092122so:OtherNaturalGasGasPipelineInvestmentsMember2019-01-012019-12-310000092122so:AlabamaPowerMemberso:OtherNaturalGasGasPipelineInvestmentsMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:OtherNaturalGasGasPipelineInvestmentsMember2019-01-012019-12-310000092122so:MississippiPowerMemberso:OtherNaturalGasGasPipelineInvestmentsMember2019-01-012019-12-310000092122so:SouthernPowerMemberso:OtherNaturalGasGasPipelineInvestmentsMember2019-01-012019-12-310000092122so:SouthernCompanyGasMemberso:OtherNaturalGasGasPipelineInvestmentsMember2019-01-012019-12-310000092122so:OtherNaturalGasWholesaleGasServicesMember2019-01-012019-12-310000092122so:OtherNaturalGasWholesaleGasServicesMemberso:AlabamaPowerMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:OtherNaturalGasWholesaleGasServicesMember2019-01-012019-12-310000092122so:OtherNaturalGasWholesaleGasServicesMemberso:MississippiPowerMember2019-01-012019-12-310000092122so:OtherNaturalGasWholesaleGasServicesMemberso:SouthernPowerMember2019-01-012019-12-310000092122so:OtherNaturalGasWholesaleGasServicesMemberso:SouthernCompanyGasMember2019-01-012019-12-310000092122so:OtherNaturalGasGasMarketingServicesMember2019-01-012019-12-310000092122so:AlabamaPowerMemberso:OtherNaturalGasGasMarketingServicesMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:OtherNaturalGasGasMarketingServicesMember2019-01-012019-12-310000092122so:MississippiPowerMemberso:OtherNaturalGasGasMarketingServicesMember2019-01-012019-12-310000092122so:SouthernPowerMemberso:OtherNaturalGasGasMarketingServicesMember2019-01-012019-12-310000092122so:SouthernCompanyGasMemberso:OtherNaturalGasGasMarketingServicesMember2019-01-012019-12-310000092122so:OtherNaturalGasOtherNaturalGasRevenuesMember2019-01-012019-12-310000092122so:OtherNaturalGasOtherNaturalGasRevenuesMemberso:AlabamaPowerMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:OtherNaturalGasOtherNaturalGasRevenuesMember2019-01-012019-12-310000092122so:OtherNaturalGasOtherNaturalGasRevenuesMemberso:MississippiPowerMember2019-01-012019-12-310000092122so:OtherNaturalGasOtherNaturalGasRevenuesMemberso:SouthernPowerMember2019-01-012019-12-310000092122so:OtherNaturalGasOtherNaturalGasRevenuesMemberso:SouthernCompanyGasMember2019-01-012019-12-310000092122so:OtherNaturalGasMember2019-01-012019-12-310000092122so:OtherNaturalGasMemberso:AlabamaPowerMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:OtherNaturalGasMember2019-01-012019-12-310000092122so:OtherNaturalGasMemberso:MississippiPowerMember2019-01-012019-12-310000092122so:OtherNaturalGasMemberso:SouthernPowerMember2019-01-012019-12-310000092122so:OtherNaturalGasMemberso:SouthernCompanyGasMember2019-01-012019-12-310000092122so:OtherRevenuesMember2019-01-012019-12-310000092122so:AlabamaPowerMemberso:OtherRevenuesMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:OtherRevenuesMember2019-01-012019-12-310000092122so:MississippiPowerMemberso:OtherRevenuesMember2019-01-012019-12-310000092122so:SouthernPowerMemberso:OtherRevenuesMember2019-01-012019-12-310000092122so:SouthernCompanyGasMemberso:OtherRevenuesMember2019-01-012019-12-310000092122so:OtherRevenueSourcesMember2019-01-012019-12-310000092122so:AlabamaPowerMemberso:OtherRevenueSourcesMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:OtherRevenueSourcesMember2019-01-012019-12-310000092122so:MississippiPowerMemberso:OtherRevenueSourcesMember2019-01-012019-12-310000092122so:SouthernPowerMemberso:OtherRevenueSourcesMember2019-01-012019-12-310000092122so:SouthernCompanyGasMemberso:OtherRevenueSourcesMember2019-01-012019-12-310000092122so:OtherAdjustmentsMember2019-01-012019-12-310000092122so:AlabamaPowerMemberso:OtherAdjustmentsMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:OtherAdjustmentsMember2019-01-012019-12-310000092122so:MississippiPowerMemberso:OtherAdjustmentsMember2019-01-012019-12-310000092122so:SouthernPowerMemberso:OtherAdjustmentsMember2019-01-012019-12-310000092122so:SouthernCompanyGasMemberso:OtherAdjustmentsMember2019-01-012019-12-310000092122so:UnregulatedDistributedGenerationMember2021-12-310000092122so:UnregulatedDistributedGenerationMember2020-12-3100000921222022-01-012021-12-3100000921222023-01-012021-12-3100000921222024-01-012021-12-3100000921222025-01-012021-12-3100000921222026-01-012021-12-3100000921222027-01-012021-12-310000092122so:AlabamaPowerMember2022-01-012021-12-3100000921222023-01-01so:AlabamaPowerMember2021-12-310000092122so:AlabamaPowerMember2024-01-012021-12-310000092122so:AlabamaPowerMember2025-01-012021-12-3100000921222026-01-01so:AlabamaPowerMember2021-12-310000092122so:AlabamaPowerMember2027-01-012021-12-310000092122so:GeorgiaPowerMember2022-01-012021-12-3100000921222023-01-01so:GeorgiaPowerMember2021-12-310000092122so:GeorgiaPowerMember2024-01-012021-12-310000092122so:GeorgiaPowerMember2025-01-012021-12-310000092122so:GeorgiaPowerMember2026-01-012021-12-310000092122so:GeorgiaPowerMember2027-01-012021-12-310000092122so:SouthernPowerMember2022-01-012021-12-3100000921222023-01-01so:SouthernPowerMember2021-12-310000092122so:SouthernPowerMember2024-01-012021-12-3100000921222025-01-01so:SouthernPowerMember2021-12-3100000921222026-01-01so:SouthernPowerMember2021-12-3100000921222027-01-01so:SouthernPowerMember2021-12-310000092122so:GeorgiaPowerMemberso:NuclearOutageMemberso:PlantVogtleNuclearUnitsOneAndTwoMember2021-01-012021-12-310000092122so:DeferredCloudImplementationCostsMember2021-12-310000092122so:DeferredCloudImplementationCostsMemberso:AlabamaPowerMember2021-12-310000092122so:GeorgiaPowerMemberso:DeferredCloudImplementationCostsMember2021-12-310000092122so:DeferredCloudImplementationCostsMemberso:MississippiPowerMember2021-12-310000092122so:DeferredCloudImplementationCostsMemberso:SouthernPowerMember2021-12-310000092122so:DeferredCloudImplementationCostsMemberso:SouthernCompanyGasMember2021-12-310000092122so:DeferredCloudImplementationCostsMember2020-12-310000092122so:DeferredCloudImplementationCostsMemberso:AlabamaPowerMember2020-12-310000092122so:GeorgiaPowerMemberso:DeferredCloudImplementationCostsMember2020-12-310000092122so:DeferredCloudImplementationCostsMemberso:MississippiPowerMember2020-12-310000092122so:DeferredCloudImplementationCostsMemberso:SouthernPowerMember2020-12-310000092122so:DeferredCloudImplementationCostsMemberso:SouthernCompanyGasMember2020-12-310000092122so:AlabamaPowerMemberso:UtilityPlantInServiceMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:UtilityPlantInServiceMember2020-01-012020-12-310000092122so:AlabamaPowerMemberso:UtilityPlantInServiceMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:UtilityPlantInServiceMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:UtilityPlantInServiceMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:UtilityPlantInServiceMember2019-01-012019-12-310000092122so:MississippiPowerMemberso:UtilityPlantInServiceMember2021-01-012021-12-310000092122so:MississippiPowerMemberso:UtilityPlantInServiceMember2020-01-012020-12-310000092122so:MississippiPowerMemberso:UtilityPlantInServiceMember2019-01-012019-12-310000092122so:SouthernCompanyGasMemberso:UtilityPlantInServiceMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberso:UtilityPlantInServiceMember2020-01-012020-12-310000092122so:SouthernCompanyGasMemberso:UtilityPlantInServiceMember2019-01-012019-12-310000092122so:UtilityPlantInServiceMember2021-12-310000092122so:UtilityPlantInServiceMember2020-12-310000092122so:SouthernCompanyGasMemberso:UtilityPlantInServiceMember2021-12-310000092122so:SouthernCompanyGasMemberso:UtilityPlantInServiceMember2020-12-310000092122us-gaap:OtherPlantInServiceMember2021-12-310000092122us-gaap:OtherPlantInServiceMember2020-12-310000092122us-gaap:OtherPlantInServiceMemberso:SouthernCompanyGasMember2021-12-310000092122us-gaap:OtherPlantInServiceMemberso:SouthernCompanyGasMember2020-12-310000092122so:SouthernCompanyGasMembersrt:MinimumMemberus-gaap:TransportationEquipmentMember2021-01-012021-12-310000092122srt:MaximumMemberso:SouthernCompanyGasMemberus-gaap:TransportationEquipmentMember2021-01-012021-12-310000092122so:StorageFacilitiesMemberso:SouthernCompanyGasMembersrt:MinimumMember2021-01-012021-12-310000092122so:StorageFacilitiesMembersrt:MaximumMemberso:SouthernCompanyGasMember2021-01-012021-12-310000092122srt:MaximumMemberso:SouthernCompanyGasMemberus-gaap:OtherAssetsMember2021-01-012021-12-310000092122us-gaap:OtherPlantInServiceMembersrt:MaximumMember2021-01-012021-12-310000092122so:NaturalGasGeneratingFacilityMembersrt:MaximumMemberso:SouthernPowerMember2021-01-012021-12-310000092122srt:MaximumMemberso:SouthernPowerMemberso:SolarGeneratingFacilityMember2021-01-012021-12-310000092122srt:MaximumMemberso:SouthernPowerMemberso:WindGeneratingFacilityMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:GreeneCountyMember2021-12-310000092122so:AlabamaPowerMemberso:PlantMillerCoalUnitsOneAndTwoMember2021-12-310000092122so:GeorgiaPowerMemberso:PlantHatchNuclearMember2021-12-310000092122so:GeorgiaPowerMemberso:PlantVogtleNuclearUnitsOneAndTwoMember2021-12-310000092122so:PlantSchererCoalUnitsOneAndTwoMemberso:GeorgiaPowerMember2021-12-310000092122so:PlantSchererUnitThreeMemberso:GeorgiaPowerMember2021-12-310000092122so:GeorgiaPowerMemberso:PlantWansleyCoalMember2021-12-310000092122so:GeorgiaPowerMemberso:RockyMountainPumpedStorageMember2021-12-310000092122so:MississippiPowerMemberso:GreeneCountyMember2021-12-310000092122so:MississippiPowerMemberso:PlantDanielUnitsOneAndTwoMember2021-12-310000092122so:DaltonPipelineNaturalGasPipelineMemberso:SouthernCompanyGasMember2021-12-310000092122so:DaltonPipelineNaturalGasPipelineMemberso:SouthernCompanyGasMember2021-01-012021-12-310000092122so:MississippiPowerMemberso:ChevronProductsCompanyMember2021-12-310000092122so:GeorgiaPowerMember2020-07-012020-09-300000092122so:GeorgiaPowerMember2021-09-012021-09-300000092122so:MississippiPowerMember2021-09-012021-09-300000092122us-gaap:EquitySecuritiesMember2021-12-310000092122us-gaap:EquitySecuritiesMemberso:AlabamaPowerMember2021-12-310000092122so:GeorgiaPowerMemberus-gaap:EquitySecuritiesMember2021-12-310000092122us-gaap:DebtSecuritiesMember2021-12-310000092122so:AlabamaPowerMemberus-gaap:DebtSecuritiesMember2021-12-310000092122so:GeorgiaPowerMemberus-gaap:DebtSecuritiesMember2021-12-310000092122so:OtherSecuritiesMember2021-12-310000092122so:OtherSecuritiesMemberso:AlabamaPowerMember2021-12-310000092122so:GeorgiaPowerMemberso:OtherSecuritiesMember2021-12-310000092122us-gaap:EquitySecuritiesMember2020-12-310000092122us-gaap:EquitySecuritiesMemberso:AlabamaPowerMember2020-12-310000092122so:GeorgiaPowerMemberus-gaap:EquitySecuritiesMember2020-12-310000092122us-gaap:DebtSecuritiesMember2020-12-310000092122so:AlabamaPowerMemberus-gaap:DebtSecuritiesMember2020-12-310000092122so:GeorgiaPowerMemberus-gaap:DebtSecuritiesMember2020-12-310000092122so:OtherSecuritiesMember2020-12-310000092122so:OtherSecuritiesMemberso:AlabamaPowerMember2020-12-310000092122so:GeorgiaPowerMemberso:OtherSecuritiesMember2020-12-310000092122so:SecuritiesHeldInFundsMemberso:FairValueIncreasesDecreasesMember2021-01-012021-12-310000092122so:SecuritiesHeldInFundsMemberso:AlabamaPowerMemberso:FairValueIncreasesDecreasesMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:SecuritiesHeldInFundsMemberso:FairValueIncreasesDecreasesMember2021-01-012021-12-310000092122so:SecuritiesHeldInFundsMemberso:FairValueIncreasesDecreasesMember2020-01-012020-12-310000092122so:SecuritiesHeldInFundsMemberso:AlabamaPowerMemberso:FairValueIncreasesDecreasesMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:SecuritiesHeldInFundsMemberso:FairValueIncreasesDecreasesMember2020-01-012020-12-310000092122so:SecuritiesHeldInFundsMemberso:FairValueIncreasesDecreasesMember2019-01-012019-12-310000092122so:SecuritiesHeldInFundsMemberso:AlabamaPowerMemberso:FairValueIncreasesDecreasesMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:SecuritiesHeldInFundsMemberso:FairValueIncreasesDecreasesMember2019-01-012019-12-310000092122so:SecuritiesHeldInFundsMemberso:UnrealizedGainLossOrWriteDownMember2021-01-012021-12-310000092122so:SecuritiesHeldInFundsMemberso:AlabamaPowerMemberso:UnrealizedGainLossOrWriteDownMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:SecuritiesHeldInFundsMemberso:UnrealizedGainLossOrWriteDownMember2021-01-012021-12-310000092122so:SecuritiesHeldInFundsMemberso:UnrealizedGainLossOrWriteDownMember2020-01-012020-12-310000092122so:SecuritiesHeldInFundsMemberso:AlabamaPowerMemberso:UnrealizedGainLossOrWriteDownMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:SecuritiesHeldInFundsMemberso:UnrealizedGainLossOrWriteDownMember2020-01-012020-12-310000092122so:SecuritiesHeldInFundsMemberso:UnrealizedGainLossOrWriteDownMember2019-01-012019-12-310000092122so:SecuritiesHeldInFundsMemberso:AlabamaPowerMemberso:UnrealizedGainLossOrWriteDownMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:SecuritiesHeldInFundsMemberso:UnrealizedGainLossOrWriteDownMember2019-01-012019-12-310000092122so:AccumulatedProvisionsForDecommissioningInternalReservesMemberso:AlabamaPowerMember2021-12-310000092122so:AccumulatedProvisionsForDecommissioningInternalReservesMemberso:AlabamaPowerMember2020-12-310000092122so:AccumulatedProvisionsForDecommissioningExternalTrustFundsMemberso:PlantFarleyMemberso:AlabamaPowerMember2021-12-310000092122so:AccumulatedProvisionsForDecommissioningExternalTrustFundsMemberso:PlantFarleyMemberso:AlabamaPowerMember2020-12-310000092122so:AccumulatedProvisionsForDecommissioningExternalTrustFundsMemberso:GeorgiaPowerMemberso:PlantHatchMember2021-12-310000092122so:AccumulatedProvisionsForDecommissioningExternalTrustFundsMemberso:GeorgiaPowerMemberso:PlantHatchMember2020-12-310000092122so:AccumulatedProvisionsForDecommissioningExternalTrustFundsMemberso:GeorgiaPowerMemberso:PlantVogtleNuclearUnitsOneAndTwoMember2021-12-310000092122so:AccumulatedProvisionsForDecommissioningExternalTrustFundsMemberso:GeorgiaPowerMemberso:PlantVogtleNuclearUnitsOneAndTwoMember2020-12-310000092122so:AccumulatedProvisionsForDecommissioningExternalTrustFundsMemberso:GeorgiaPowerMember2021-12-310000092122so:AccumulatedProvisionsForDecommissioningExternalTrustFundsMemberso:GeorgiaPowerMember2020-12-310000092122so:PlantFarleyMemberso:AlabamaPowerMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:PlantHatchMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:PlantVogtleNuclearUnitsOneAndTwoMember2021-01-012021-12-310000092122so:PlantFarleyMemberso:AlabamaPowerMemberso:SiteStudyCostRadiatedStructuresMember2021-12-310000092122so:GeorgiaPowerMemberso:SiteStudyCostRadiatedStructuresMemberso:PlantHatchMember2021-12-310000092122so:GeorgiaPowerMemberso:PlantVogtleNuclearUnitsOneAndTwoMemberso:SiteStudyCostRadiatedStructuresMember2021-12-310000092122so:PlantFarleyMemberso:AlabamaPowerMemberso:SpentFuelManagementMember2021-12-310000092122so:GeorgiaPowerMemberso:SpentFuelManagementMemberso:PlantHatchMember2021-12-310000092122so:GeorgiaPowerMemberso:PlantVogtleNuclearUnitsOneAndTwoMemberso:SpentFuelManagementMember2021-12-310000092122so:PlantFarleyMemberso:AlabamaPowerMemberso:SiteStudyCostNonRadiatedStructuresMember2021-12-310000092122so:GeorgiaPowerMemberso:PlantHatchMemberso:SiteStudyCostNonRadiatedStructuresMember2021-12-310000092122so:GeorgiaPowerMemberso:PlantVogtleNuclearUnitsOneAndTwoMemberso:SiteStudyCostNonRadiatedStructuresMember2021-12-310000092122so:PlantFarleyMemberso:AlabamaPowerMember2021-12-310000092122so:GeorgiaPowerMemberso:PlantHatchMember2021-12-310000092122so:GeorgiaPowerMemberso:PlantHatchandPlantVogtleUnits1And2Member2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:PlantHatchandPlantVogtleUnits1And2Member2019-01-012019-12-310000092122so:AlabamaPowerMemberso:SouthernElectricGeneratingCompanyMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:SouthernElectricGeneratingCompanyMember2020-01-012020-12-310000092122so:AlabamaPowerMemberso:SouthernElectricGeneratingCompanyMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:SouthernElectricGeneratingCompanyMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:SouthernElectricGeneratingCompanyMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:SouthernElectricGeneratingCompanyMember2019-01-012019-12-310000092122so:AlabamaPowerMemberso:SouthernElectricGeneratingCompanyMember2021-12-310000092122so:SPSolarHoldingsILPMemberso:SouthernPowerMember2018-01-012018-12-310000092122so:WhollyOwnedSubsidiaryOfSouthernPowerMemberso:SPSolarHoldingsILPMemberus-gaap:GeneralPartnerMemberso:SouthernPowerMember2018-01-012018-12-310000092122so:WhollyOwnedSubsidiaryOfSouthernPowerMemberso:SPSolarHoldingsILPMemberso:SouthernPowerMember2018-01-012018-12-310000092122us-gaap:VariableInterestEntityPrimaryBeneficiaryMemberso:SouthernPowerMemberso:SPSolarHoldingsILPMember2021-12-310000092122us-gaap:VariableInterestEntityPrimaryBeneficiaryMemberso:SouthernPowerMemberso:SPSolarHoldingsILPMember2020-12-310000092122so:SouthernPowerMemberso:SPSolarHoldingsILPMember2021-01-012021-12-310000092122so:SPSolarHoldingsILPMemberso:GlobalAtlanticMember2021-01-012021-12-310000092122so:SPWindMemberso:SouthernPowerMember2018-01-012018-12-31so:investor0000092122so:WhollyOwnedSubsidiaryOfSouthernPowerMemberso:SouthernPowerMemberso:SPWindMember2018-01-012018-12-310000092122so:SouthernPowerMemberso:SPWindMember2018-01-012018-12-310000092122so:SPWindMemberus-gaap:VariableInterestEntityPrimaryBeneficiaryMemberso:SouthernPowerMember2021-12-310000092122so:SPWindMemberus-gaap:VariableInterestEntityPrimaryBeneficiaryMemberso:SouthernPowerMember2020-12-310000092122so:SPWindMemberso:SouthernPowerMember2021-01-012021-12-310000092122so:FinancialInvestorsMemberso:SPWindMember2021-01-012021-12-310000092122us-gaap:VariableInterestEntityPrimaryBeneficiaryMemberso:SouthernPowerMemberso:OtherVariableInterestEntitiesMember2021-12-310000092122us-gaap:VariableInterestEntityPrimaryBeneficiaryMemberso:SouthernPowerMemberso:OtherVariableInterestEntitiesMember2020-12-310000092122us-gaap:SubsequentEventMemberso:SouthernPowerMember2022-01-012022-02-160000092122so:SouthernCompanyGasMemberso:SNGMember2021-12-310000092122so:SouthernCompanyGasMemberso:SNGMember2020-12-310000092122so:SouthernCompanyGasMemberso:PennEastPipelinesMember2021-12-310000092122so:SouthernCompanyGasMemberso:PennEastPipelinesMember2020-12-310000092122so:SouthernCompanyGasMemberso:OtherMember2021-12-310000092122so:SouthernCompanyGasMemberso:OtherMember2020-12-310000092122so:SouthernCompanyGasMemberso:PennEastPipelinesMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberso:SNGMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberso:SNGMember2020-01-012020-12-310000092122so:SouthernCompanyGasMemberso:SNGMember2019-01-012019-12-310000092122so:AtlanticCoastPipelineMemberso:SouthernCompanyGasMember2021-01-012021-12-310000092122so:AtlanticCoastPipelineMemberso:SouthernCompanyGasMember2020-01-012020-12-310000092122so:AtlanticCoastPipelineMemberso:SouthernCompanyGasMember2019-01-012019-12-310000092122so:SouthernCompanyGasMemberso:PennEastPipelinesMember2020-01-012020-12-310000092122so:SouthernCompanyGasMemberso:PennEastPipelinesMember2019-01-012019-12-310000092122so:SouthernCompanyGasMemberso:OtherMember2021-01-012021-12-310000092122so:SouthernCompanyGasMemberso:OtherMember2020-01-012020-12-310000092122so:SouthernCompanyGasMemberso:OtherMember2019-01-012019-12-310000092122so:SouthernCompanyGasMemberso:PennEastPipelinesMember2014-12-310000092122so:SouthernCompanyGasMemberso:PennEastPipelinesMember2021-04-012021-06-300000092122so:SouthernCompanyGasMemberso:PennEastPipelinesMember2021-07-012021-09-300000092122us-gaap:SeniorNotesMember2021-12-310000092122us-gaap:SeniorNotesMember2020-12-310000092122us-gaap:JuniorSubordinatedDebtMember2021-12-310000092122us-gaap:JuniorSubordinatedDebtMember2020-12-310000092122so:FederalFinancingBankLoansMember2021-12-310000092122so:FederalFinancingBankLoansMember2020-12-310000092122so:PollutionControlRevenueBondsMember2021-12-310000092122so:PollutionControlRevenueBondsMember2020-12-310000092122so:FirstMortgageBondsMember2021-12-310000092122so:FirstMortgageBondsMember2020-12-310000092122us-gaap:MediumTermNotesMember2021-12-310000092122us-gaap:MediumTermNotesMember2020-12-310000092122so:OtherLongTermDebtMember2021-12-310000092122so:OtherLongTermDebtMember2020-12-310000092122so:OtherRevenueBondsMember2021-12-310000092122so:OtherRevenueBondsMember2020-12-310000092122so:AffiliatedTrustsMember2021-12-310000092122so:AffiliatedTrustsMember2020-12-310000092122so:AlabamaPowerMemberus-gaap:SeniorNotesMember2021-12-310000092122so:AlabamaPowerMemberus-gaap:SeniorNotesMember2020-12-310000092122so:AlabamaPowerMemberso:PollutionControlRevenueBondsMember2021-12-310000092122so:AlabamaPowerMemberso:PollutionControlRevenueBondsMember2020-12-310000092122so:AlabamaPowerMemberso:OtherLongTermDebtMember2021-12-310000092122so:AlabamaPowerMemberso:OtherLongTermDebtMember2020-12-310000092122so:AlabamaPowerMemberso:AffiliatedTrustsMember2021-12-310000092122so:AlabamaPowerMemberso:AffiliatedTrustsMember2020-12-310000092122so:GeorgiaPowerMemberus-gaap:SeniorNotesMember2021-12-310000092122so:GeorgiaPowerMemberus-gaap:SeniorNotesMember2020-12-310000092122so:GeorgiaPowerMemberus-gaap:JuniorSubordinatedDebtMember2021-12-310000092122so:GeorgiaPowerMemberus-gaap:JuniorSubordinatedDebtMember2020-12-310000092122so:GeorgiaPowerMemberso:FederalFinancingBankLoansMember2021-12-310000092122so:GeorgiaPowerMemberso:FederalFinancingBankLoansMember2020-12-310000092122so:GeorgiaPowerMemberso:PollutionControlRevenueBondsMember2021-12-310000092122so:GeorgiaPowerMemberso:PollutionControlRevenueBondsMember2020-12-310000092122so:GeorgiaPowerMemberso:OtherLongTermDebtMember2021-12-310000092122so:GeorgiaPowerMemberso:OtherLongTermDebtMember2020-12-310000092122so:MississippiPowerMemberus-gaap:SeniorNotesMember2021-12-310000092122so:MississippiPowerMemberus-gaap:SeniorNotesMember2020-12-310000092122so:MississippiPowerMemberso:PollutionControlRevenueBondsMember2021-12-310000092122so:MississippiPowerMemberso:PollutionControlRevenueBondsMember2020-12-310000092122so:MississippiPowerMemberso:OtherRevenueBondsMember2021-12-310000092122so:MississippiPowerMemberso:OtherRevenueBondsMember2020-12-310000092122so:MississippiPowerMemberso:OtherLongTermDebtMember2021-12-310000092122so:MississippiPowerMemberso:OtherLongTermDebtMember2020-12-310000092122us-gaap:SeniorNotesMemberso:SouthernPowerMember2021-12-310000092122us-gaap:SeniorNotesMemberso:SouthernPowerMember2020-12-310000092122so:SouthernCompanyGasMemberus-gaap:SeniorNotesMember2021-12-310000092122so:SouthernCompanyGasMemberus-gaap:SeniorNotesMember2020-12-310000092122so:SouthernCompanyGasMemberso:FirstMortgageBondsMember2021-12-310000092122so:SouthernCompanyGasMemberso:FirstMortgageBondsMember2020-12-310000092122us-gaap:MediumTermNotesMemberso:SouthernCompanyGasMember2021-12-310000092122us-gaap:MediumTermNotesMemberso:SouthernCompanyGasMember2020-12-310000092122us-gaap:JuniorSubordinatedDebtMemberso:Series2019ARemarketableJuniorSubordinatedNotesMember2019-12-310000092122so:EuroDenominatedDebtMemberso:SouthernPowerMember2021-12-310000092122so:GeorgiaPowerMemberso:FFBCreditFacilityMember2019-03-012019-03-310000092122so:GeorgiaPowerMemberso:FFBCreditFacilityMember2019-03-310000092122so:GeorgiaPowerMemberso:FFBCreditFacilityMember2020-06-012020-06-300000092122so:GeorgiaPowerMemberso:FFBCreditFacilityMember2020-12-012020-12-310000092122so:GeorgiaPowerMemberso:FFBCreditFacilityMember2020-06-300000092122so:GeorgiaPowerMemberso:FFBCreditFacilityMember2021-12-310000092122so:GeorgiaPowerMemberso:FFBCreditFacilityMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:FFBCreditFacilityMember2020-12-310000092122us-gaap:JuniorSubordinatedDebtMemberso:Series2019ARemarketableJuniorSubordinatedNotesMember2019-01-012019-12-310000092122so:Series2019AAndSeries2019BRemarketableJuniorSubordinatedNotesMemberus-gaap:JuniorSubordinatedDebtMember2019-01-012019-12-310000092122so:Series2019AAndSeries2019BRemarketableJuniorSubordinatedNotesMemberus-gaap:JuniorSubordinatedDebtMember2019-12-310000092122so:Series2019AAndSeries2019BRemarketableJuniorSubordinatedNotesMembersrt:MinimumMemberso:AntiDilutionScenarioOneMemberus-gaap:JuniorSubordinatedDebtMember2019-12-310000092122so:Series2019AAndSeries2019BRemarketableJuniorSubordinatedNotesMemberso:AntiDilutionScenarioOneMemberus-gaap:JuniorSubordinatedDebtMember2019-12-310000092122so:Series2019AAndSeries2019BRemarketableJuniorSubordinatedNotesMemberso:AntiDilutionScenarioTwoMembersrt:MaximumMemberus-gaap:JuniorSubordinatedDebtMember2019-12-310000092122so:Series2019AAndSeries2019BRemarketableJuniorSubordinatedNotesMemberso:AntiDilutionScenarioTwoMembersrt:MinimumMemberus-gaap:JuniorSubordinatedDebtMember2019-12-310000092122so:Series2019AAndSeries2019BRemarketableJuniorSubordinatedNotesMemberso:AntiDilutionScenarioTwoMemberus-gaap:JuniorSubordinatedDebtMember2019-01-012019-12-310000092122so:Series2019AAndSeries2019BRemarketableJuniorSubordinatedNotesMembersrt:MaximumMemberso:AntiDilutionScenarioThreeMemberus-gaap:JuniorSubordinatedDebtMember2019-12-310000092122so:Series2019AAndSeries2019BRemarketableJuniorSubordinatedNotesMemberso:AntiDilutionScenarioThreeMemberus-gaap:JuniorSubordinatedDebtMember2019-12-310000092122so:Series2019AAndSeries2019BRemarketableJuniorSubordinatedNotesMemberus-gaap:JuniorSubordinatedDebtMember2021-12-310000092122us-gaap:JuniorSubordinatedDebtMemberso:Series2019BRemarketableJuniorSubordinatedNotesMember2019-12-310000092122so:OtherSubsidiariesMember2021-12-310000092122so:ContinuingLetterOfCreditFacilityAMemberso:SouthernPowerMember2021-12-310000092122so:ContinuingLetterOfCreditFacilityBMemberso:SouthernPowerMember2021-12-310000092122us-gaap:SubsequentEventMemberso:ContinuingLetterOfCreditFacilityBMemberso:SouthernPowerMember2022-02-160000092122so:SouthernCompanyGasCapitalMember2021-12-310000092122so:PowerPurchaseAgreementMemberso:SouthernPowerMember2021-12-310000092122so:PowerPurchaseAgreementMemberso:SouthernPowerMember2020-12-310000092122us-gaap:CommercialPaperMember2021-12-310000092122us-gaap:CommercialPaperMember2020-12-310000092122so:ShortTermBankDebtMember2021-12-310000092122so:ShortTermBankDebtMember2020-12-310000092122so:GeorgiaPowerMemberus-gaap:CommercialPaperMember2021-12-310000092122so:GeorgiaPowerMemberus-gaap:CommercialPaperMember2020-12-310000092122us-gaap:CommercialPaperMemberso:MississippiPowerMember2021-12-310000092122us-gaap:CommercialPaperMemberso:MississippiPowerMember2020-12-310000092122us-gaap:CommercialPaperMemberso:SouthernPowerMember2021-12-310000092122us-gaap:CommercialPaperMemberso:SouthernPowerMember2020-12-310000092122so:SouthernCompanyGasCapitalMemberus-gaap:CommercialPaperMember2021-12-310000092122so:SouthernCompanyGasCapitalMemberus-gaap:CommercialPaperMember2020-12-310000092122us-gaap:CommercialPaperMemberso:NicorGasMember2021-12-310000092122us-gaap:CommercialPaperMemberso:NicorGasMember2020-12-310000092122so:ShortTermBankDebtMemberso:NicorGasMember2021-12-310000092122so:ShortTermBankDebtMemberso:NicorGasMember2020-12-310000092122us-gaap:CommercialPaperMemberso:SouthernCompanyGasMember2021-12-310000092122us-gaap:CommercialPaperMemberso:SouthernCompanyGasMember2020-12-310000092122so:SouthernCompanyCommonStockMember2021-12-310000092122so:FourPointNineTwoPercentRedeemablePreferredStockMemberso:AlabamaPowerMember2021-01-012021-12-310000092122so:FourPointNineTwoPercentRedeemablePreferredStockMemberso:AlabamaPowerMember2021-12-310000092122so:AlabamaPowerMemberso:FourPointSevenTwoPercentRedeemablePreferredStockMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:FourPointSevenTwoPercentRedeemablePreferredStockMember2021-12-310000092122so:FourPointSixFourPercentRedeemablePreferredStockMemberso:AlabamaPowerMember2021-01-012021-12-310000092122so:FourPointSixFourPercentRedeemablePreferredStockMemberso:AlabamaPowerMember2021-12-310000092122so:FourPointSixZeroPercentRedeemablePreferredStockMemberso:AlabamaPowerMember2021-01-012021-12-310000092122so:FourPointSixZeroPercentRedeemablePreferredStockMemberso:AlabamaPowerMember2021-12-310000092122so:AlabamaPowerMemberso:FourPointFiveTwoPercentRedeemablePreferredStockMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:FourPointFiveTwoPercentRedeemablePreferredStockMember2021-12-310000092122so:AlabamaPowerMemberso:FourPointTwoZeroPercentRedeemablePreferredStockMember2021-01-012021-12-310000092122so:AlabamaPowerMemberso:FourPointTwoZeroPercentRedeemablePreferredStockMember2021-12-310000092122so:FivePercentClassAPreferredStockMemberso:AlabamaPowerMember2021-01-012021-12-310000092122so:FivePercentClassAPreferredStockMemberso:AlabamaPowerMember2021-12-310000092122so:FivePercentClassAPreferredStockMembersrt:ScenarioForecastMemberso:AlabamaPowerMember2022-09-300000092122so:SouthernCompanyGasMemberso:SouthernCompanyGasCapitalMember2021-12-310000092122so:ElectricGeneratingUnitsMember2021-12-310000092122so:AlabamaPowerMemberso:ElectricGeneratingUnitsMember2021-12-310000092122so:GeorgiaPowerMemberso:ElectricGeneratingUnitsMember2021-12-310000092122so:MississippiPowerMemberso:ElectricGeneratingUnitsMember2021-12-310000092122so:ElectricGeneratingUnitsMemberso:SouthernPowerMember2021-12-310000092122so:SouthernCompanyGasMemberso:ElectricGeneratingUnitsMember2021-12-310000092122us-gaap:LandAndBuildingMember2021-12-310000092122so:AlabamaPowerMemberus-gaap:LandAndBuildingMember2021-12-310000092122so:GeorgiaPowerMemberus-gaap:LandAndBuildingMember2021-12-310000092122so:MississippiPowerMemberus-gaap:LandAndBuildingMember2021-12-310000092122us-gaap:LandAndBuildingMemberso:SouthernPowerMember2021-12-310000092122so:SouthernCompanyGasMemberus-gaap:LandAndBuildingMember2021-12-310000092122so:CommunicationTowersMember2021-12-310000092122so:CommunicationTowersMemberso:AlabamaPowerMember2021-12-310000092122so:GeorgiaPowerMemberso:CommunicationTowersMember2021-12-310000092122so:CommunicationTowersMemberso:MississippiPowerMember2021-12-310000092122so:CommunicationTowersMemberso:SouthernPowerMember2021-12-310000092122so:CommunicationTowersMemberso:SouthernCompanyGasMember2021-12-310000092122so:RailcarsMember2021-12-310000092122so:RailcarsMemberso:AlabamaPowerMember2021-12-310000092122so:GeorgiaPowerMemberso:RailcarsMember2021-12-310000092122so:RailcarsMemberso:MississippiPowerMember2021-12-310000092122so:RailcarsMemberso:SouthernPowerMember2021-12-310000092122so:RailcarsMemberso:SouthernCompanyGasMember2021-12-310000092122us-gaap:PropertyPlantAndEquipmentOtherTypesMember2021-12-310000092122so:AlabamaPowerMemberus-gaap:PropertyPlantAndEquipmentOtherTypesMember2021-12-310000092122so:GeorgiaPowerMemberus-gaap:PropertyPlantAndEquipmentOtherTypesMember2021-12-310000092122us-gaap:PropertyPlantAndEquipmentOtherTypesMemberso:MississippiPowerMember2021-12-310000092122us-gaap:PropertyPlantAndEquipmentOtherTypesMemberso:SouthernPowerMember2021-12-310000092122us-gaap:PropertyPlantAndEquipmentOtherTypesMemberso:SouthernCompanyGasMember2021-12-310000092122so:ElectricGeneratingUnitsMember2020-12-310000092122so:AlabamaPowerMemberso:ElectricGeneratingUnitsMember2020-12-310000092122so:GeorgiaPowerMemberso:ElectricGeneratingUnitsMember2020-12-310000092122so:MississippiPowerMemberso:ElectricGeneratingUnitsMember2020-12-310000092122so:ElectricGeneratingUnitsMemberso:SouthernPowerMember2020-12-310000092122so:SouthernCompanyGasMemberso:ElectricGeneratingUnitsMember2020-12-310000092122us-gaap:LandAndBuildingMember2020-12-310000092122so:AlabamaPowerMemberus-gaap:LandAndBuildingMember2020-12-310000092122so:GeorgiaPowerMemberus-gaap:LandAndBuildingMember2020-12-310000092122so:MississippiPowerMemberus-gaap:LandAndBuildingMember2020-12-310000092122us-gaap:LandAndBuildingMemberso:SouthernPowerMember2020-12-310000092122so:SouthernCompanyGasMemberus-gaap:LandAndBuildingMember2020-12-310000092122so:CommunicationTowersMember2020-12-310000092122so:CommunicationTowersMemberso:AlabamaPowerMember2020-12-310000092122so:GeorgiaPowerMemberso:CommunicationTowersMember2020-12-310000092122so:CommunicationTowersMemberso:MississippiPowerMember2020-12-310000092122so:CommunicationTowersMemberso:SouthernPowerMember2020-12-310000092122so:CommunicationTowersMemberso:SouthernCompanyGasMember2020-12-310000092122so:RailcarsMember2020-12-310000092122so:RailcarsMemberso:AlabamaPowerMember2020-12-310000092122so:GeorgiaPowerMemberso:RailcarsMember2020-12-310000092122so:RailcarsMemberso:MississippiPowerMember2020-12-310000092122so:RailcarsMemberso:SouthernPowerMember2020-12-310000092122so:RailcarsMemberso:SouthernCompanyGasMember2020-12-310000092122us-gaap:PropertyPlantAndEquipmentOtherTypesMember2020-12-310000092122so:AlabamaPowerMemberus-gaap:PropertyPlantAndEquipmentOtherTypesMember2020-12-310000092122so:GeorgiaPowerMemberus-gaap:PropertyPlantAndEquipmentOtherTypesMember2020-12-310000092122us-gaap:PropertyPlantAndEquipmentOtherTypesMemberso:MississippiPowerMember2020-12-310000092122us-gaap:PropertyPlantAndEquipmentOtherTypesMemberso:SouthernPowerMember2020-12-310000092122us-gaap:PropertyPlantAndEquipmentOtherTypesMemberso:SouthernCompanyGasMember2020-12-310000092122srt:MaximumMemberus-gaap:BuildingMember2021-01-012021-12-310000092122us-gaap:LandMembersrt:MaximumMember2021-01-012021-12-310000092122so:CommunicationTowersMembersrt:MaximumMember2021-01-012021-12-310000092122so:CommunicationTowersMember2021-01-012021-12-310000092122so:AlabamaPowerMembersrt:MinimumMemberso:ElectricGeneratingUnitsMember2021-12-310000092122so:AlabamaPowerMembersrt:MaximumMemberso:ElectricGeneratingUnitsMember2021-12-310000092122srt:AffiliatedEntityMemberso:GeorgiaPowerMemberso:ElectricGeneratingUnitsMember2021-12-310000092122srt:AffiliatedEntityMemberso:GeorgiaPowerMemberso:ElectricGeneratingUnitsMember2020-12-310000092122so:AssetsSubjectToPowerPurchaseAgreementMember2021-12-310000092122so:AssetsSubjectToPowerPurchaseAgreementMemberso:AlabamaPowerMember2021-12-310000092122so:GeorgiaPowerMemberso:AssetsSubjectToPowerPurchaseAgreementMember2021-12-310000092122so:AssetsSubjectToPowerPurchaseAgreementMember2020-12-310000092122so:AssetsSubjectToPowerPurchaseAgreementMemberso:AlabamaPowerMember2020-12-310000092122so:GeorgiaPowerMemberso:AssetsSubjectToPowerPurchaseAgreementMember2020-12-310000092122so:AssetsSubjectToPowerPurchaseAgreementMember2021-01-012021-12-310000092122so:AssetsSubjectToPowerPurchaseAgreementMemberso:AlabamaPowerMember2021-01-012021-12-310000092122so:GeorgiaPowerMemberso:AssetsSubjectToPowerPurchaseAgreementMember2021-01-012021-12-310000092122so:AssetsSubjectToPowerPurchaseAgreementMember2020-01-012020-12-310000092122so:AssetsSubjectToPowerPurchaseAgreementMemberso:AlabamaPowerMember2020-01-012020-12-310000092122so:GeorgiaPowerMemberso:AssetsSubjectToPowerPurchaseAgreementMember2020-01-012020-12-310000092122so:AssetsSubjectToPowerPurchaseAgreementMember2019-01-012019-12-310000092122so:AssetsSubjectToPowerPurchaseAgreementMemberso:AlabamaPowerMember2019-01-012019-12-310000092122so:GeorgiaPowerMemberso:AssetsSubjectToPowerPurchaseAgreementMember2019-01-012019-12-310000092122so:OutdoorLightingMemberso:TraditionalElectricOperatingCompaniesMembersrt:MaximumMember2021-12-310000092122srt:MaximumMemberso:MississippiPowerMemberso:ElectricGeneratingUnitsMember2021-12-310000092122srt:MaximumMemberso:ElectricGeneratingUnitsMemberso:SouthernPowerMember2021-12-310000092122srt:MaximumMemberso:SouthernCompanyGasMember2021-01-012021-12-310000092122so:FuelCellsMembersrt:MaximumMember2021-12-310000092122so:SouthernPowerMember2021-10-012021-12-310000092122so:MississippiPowerMemberso:OtherPropertyAndInvestmentsMember2021-12-310000092122so:OtherAccountsNotesAndLoansReceivableMemberso:SouthernPowerMember2021-12-31so:leveraged_lease0000092122so:DomesticAndInternationalLeveragedLeaseMember2020-12-310000092122so:DomesticAndInternationalLeveragedLeaseMember2021-01-012021-12-310000092122so:DomesticAndInternationalLeveragedLeaseMember2020-01-012020-12-310000092122so:DomesticAndInternationalLeveragedLeaseMember2019-01-012019-12-3100000921222019-10-012019-12-3100000921222020-04-012020-06-300000092122so:UnrealizedTaxCreditsMemberus-gaap:OtherNoncurrentAssetsMemberso:DeferredChargesRelatedToIncomeTaxesCurrentMemberso:SouthernPowerMember2021-12-310000092122so:UnrealizedTaxCreditsMemberus-gaap:OtherNoncurrentAssetsMemberso:DeferredChargesRelatedToIncomeTaxesCurrentMemberso:SouthernPowerMember2020-12-310000092122so:UnrealizedTaxCreditsMemberus-gaap:OtherNoncurrentAssetsMember