atgff-20221231 0001695519 2022 FY false 2022 FY 0001695519 P1Y 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 P6Y P3Y P3Y 0001695519 2022-01-01 2022-12-31 0001695519 dei:BusinessContactMember 2022-01-01 2022-12-31 0001695519 us-gaap:CommonStockMember 2022-12-31 xbrli:shares 0001695519 2022-12-31 iso4217:CAD 0001695519 2021-12-31 0001695519 us-gaap:CommonStockMember 2021-12-31 0001695519 2021-01-01 2021-12-31 0001695519 us-gaap:RetainedEarningsMember 2021-01-01 2021-12-31 iso4217:CAD xbrli:shares 0001695519 us-gaap:CommonStockMember 2020-12-31 0001695519 us-gaap:CommonStockMember 2022-01-01 2022-12-31 0001695519 us-gaap:CommonStockMember 2021-01-01 2021-12-31 0001695519 us-gaap:PreferredStockMember 2021-12-31 0001695519 us-gaap:PreferredStockMember 2020-12-31 0001695519 us-gaap:PreferredStockMember 2022-01-01 2022-12-31 0001695519 us-gaap:PreferredStockMember 2021-01-01 2021-12-31 0001695519 us-gaap:PreferredStockMember 2022-12-31 0001695519 us-gaap:AdditionalPaidInCapitalMember 2021-12-31 0001695519 us-gaap:AdditionalPaidInCapitalMember 2020-12-31 0001695519 us-gaap:AdditionalPaidInCapitalMember 2022-01-01 2022-12-31 0001695519 us-gaap:AdditionalPaidInCapitalMember 2021-01-01 2021-12-31 0001695519 us-gaap:AdditionalPaidInCapitalMember atgff:PetrogasEnergyCorporationMember 2022-01-01 2022-12-31 0001695519 us-gaap:AdditionalPaidInCapitalMember 2022-12-31 0001695519 us-gaap:RetainedEarningsMember 2021-12-31 0001695519 us-gaap:RetainedEarningsMember 2020-12-31 0001695519 us-gaap:RetainedEarningsMember 2022-01-01 2022-12-31 0001695519 us-gaap:RetainedEarningsMember 2022-12-31 0001695519 us-gaap:AccumulatedOtherComprehensiveIncomeMember 2021-12-31 0001695519 us-gaap:AccumulatedOtherComprehensiveIncomeMember 2020-12-31 0001695519 us-gaap:AccumulatedOtherComprehensiveIncomeMember 2022-01-01 2022-12-31 0001695519 us-gaap:AccumulatedOtherComprehensiveIncomeMember 2021-01-01 2021-12-31 0001695519 us-gaap:AccumulatedOtherComprehensiveIncomeMember 2022-12-31 0001695519 us-gaap:ParentMember 2022-12-31 0001695519 us-gaap:ParentMember 2021-12-31 0001695519 us-gaap:NoncontrollingInterestMember 2021-12-31 0001695519 us-gaap:NoncontrollingInterestMember 2020-12-31 0001695519 us-gaap:NoncontrollingInterestMember 2022-01-01 2022-12-31 0001695519 us-gaap:NoncontrollingInterestMember 2021-01-01 2021-12-31 0001695519 us-gaap:NoncontrollingInterestMember 2022-12-31 0001695519 2020-12-31 0001695519 atgff:CINGSAMember atgff:MidstreamSegmentMember 2022-12-31 xbrli:pure 0001695519 atgff:UtilitiesSegmentMember 2022-01-01 2022-12-31 atgff:customer iso4217:USD utr:MW 0001695519 atgff:UtilitiesSegmentMember srt:MinimumMember 2022-01-01 2022-12-31 0001695519 srt:MaximumMember atgff:UtilitiesSegmentMember 2022-01-01 2022-12-31 0001695519 srt:MinimumMember atgff:MidstreamSegmentMember 2022-01-01 2022-12-31 0001695519 srt:MaximumMember atgff:MidstreamSegmentMember 2022-01-01 2022-12-31 0001695519 us-gaap:CorporateNonSegmentMember srt:MinimumMember 2022-01-01 2022-12-31 0001695519 srt:MaximumMember us-gaap:CorporateNonSegmentMember 2022-01-01 2022-12-31 0001695519 atgff:EnergyServicesRelationshipsMember 2022-01-01 2022-12-31 0001695519 atgff:SoftwareMember srt:MinimumMember 2022-01-01 2022-12-31 0001695519 atgff:SoftwareMember srt:MaximumMember 2022-01-01 2022-12-31 0001695519 atgff:ExtractionAndTransmissionContractsMember 2022-01-01 2022-12-31 0001695519 srt:MaximumMember us-gaap:CommodityContractMember 2022-01-01 2022-12-31 0001695519 us-gaap:PerformanceSharesMember srt:MinimumMember 2022-01-01 2022-12-31 0001695519 us-gaap:PerformanceSharesMember srt:MaximumMember 2022-01-01 2022-12-31 0001695519 atgff:PetrogasEnergyCorporationMember 2022-07-05 0001695519 atgff:PetrogasEnergyCorporationMember 2022-07-05 2022-07-05 0001695519 atgff:PetrogasEnergyCorporationMember 2022-12-31 0001695519 atgff:PetrogasEnergyCorporationMember 2022-01-01 2022-12-31 0001695519 atgff:EnergyStorageDevelopmentProjectMember us-gaap:DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember 2022-03-31 0001695519 atgff:EnergyStorageDevelopmentProjectMember us-gaap:DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember 2022-01-01 2022-03-31 0001695519 us-gaap:SubsequentEventMember atgff:EnergyStorageDevelopmentProjectMember us-gaap:DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember 2023-02-01 2023-02-28 0001695519 us-gaap:DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember atgff:AitkenCreekProcessingFacilitiesMember 2022-04-12 2022-04-12 0001695519 us-gaap:DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember atgff:AitkenCreekProcessingFacilitiesMember 2022-01-01 2022-12-31 0001695519 us-gaap:DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember atgff:BrushIIMember 2022-05-27 0001695519 us-gaap:DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember atgff:BrushIIMember 2022-05-27 2022-05-27 0001695519 us-gaap:DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember atgff:BrushIIMember 2022-01-01 2022-12-31 0001695519 us-gaap:DisposalGroupHeldforsaleNotDiscontinuedOperationsMember atgff:AlaskanUtilitiesMember 2022-01-01 2022-12-31 0001695519 us-gaap:DisposalGroupHeldforsaleNotDiscontinuedOperationsMember atgff:AlaskanUtilitiesMember 2022-12-31 0001695519 us-gaap:DisposalGroupHeldforsaleNotDiscontinuedOperationsMember atgff:AlaskanUtilitiesMember 2021-12-31 0001695519 us-gaap:DisposalGroupHeldforsaleNotDiscontinuedOperationsMember atgff:AlaskanUtilitiesMember 2022-05-26 2022-05-26 0001695519 atgff:MidstreamSegmentMember 2022-01-01 2022-12-31 0001695519 atgff:MidstreamSegmentMember 2021-01-01 2021-12-31 0001695519 atgff:CorporateAndOtherSegmentMember 2022-01-01 2022-12-31 0001695519 atgff:CorporateAndOtherSegmentMember 2021-01-01 2021-12-31 0001695519 atgff:RateRegulatedUtilitiesMember 2022-12-31 0001695519 atgff:RateRegulatedUtilitiesMember 2021-12-31 0001695519 2022-05-26 0001695519 atgff:UtilitiesSegmentMember 2022-12-31 0001695519 atgff:UtilitiesSegmentMember 2021-12-31 0001695519 atgff:MidstreamSegmentMember 2022-12-31 0001695519 atgff:MidstreamSegmentMember 2021-12-31 0001695519 us-gaap:CorporateMember 2022-12-31 0001695519 us-gaap:CorporateMember 2021-12-31 0001695519 us-gaap:DisposalGroupHeldforsaleNotDiscontinuedOperationsMember 2022-12-31 0001695519 us-gaap:DisposalGroupHeldforsaleNotDiscontinuedOperationsMember 2021-12-31 0001695519 atgff:ExtractionAndTransmissionContractsMember 2022-12-31 0001695519 atgff:ExtractionAndTransmissionContractsMember 2021-12-31 0001695519 atgff:EnergyServicesRelationshipsMember 2022-12-31 0001695519 atgff:EnergyServicesRelationshipsMember 2021-12-31 0001695519 atgff:SoftwareMember 2022-12-31 0001695519 atgff:SoftwareMember 2021-12-31 0001695519 atgff:LandRightsMember 2022-12-31 0001695519 atgff:LandRightsMember 2021-12-31 0001695519 us-gaap:CommodityContractMember 2022-12-31 0001695519 us-gaap:CommodityContractMember 2021-12-31 0001695519 atgff:RILELimitedPartnerMember atgff:AltagasLPGMember 2017-05-05 2017-05-05 0001695519 atgff:RILELimitedPartnerMember atgff:VopakMember 2017-05-05 2017-05-05 0001695519 us-gaap:VariableInterestEntityPrimaryBeneficiaryMember 2022-12-31 0001695519 us-gaap:VariableInterestEntityPrimaryBeneficiaryMember 2021-12-31 0001695519 atgff:FixedToFixedRateSubordinatedNotesSeries1Member atgff:AltaGasHybridTrustMember 2022-01-11 0001695519 us-gaap:SeriesAPreferredStockMember atgff:AltaGasHybridTrustMember 2022-01-11 0001695519 atgff:FixedToFixedRateSubordinatedNotesSeries2Member atgff:AltaGasHybridTrustMember 2022-08-17 0001695519 us-gaap:SeriesBPreferredStockMember atgff:AltaGasHybridTrustMember 2022-08-17 atgff:cavern 0001695519 country:CA atgff:StrathconaStorageLPMember 2022-07-04 0001695519 country:CA atgff:StrathconaStorageLPMember 2022-07-05 0001695519 country:CA atgff:StrathconaStorageLPMember 2022-12-31 0001695519 country:CA atgff:StrathconaStorageLPMember 2021-12-31 0001695519 country:US atgff:ConstitutionPipelineLLCMember 2022-12-31 0001695519 country:US atgff:ConstitutionPipelineLLCMember 2021-12-31 0001695519 country:US atgff:ConstitutionPipelineLLCMember 2022-01-01 2022-12-31 0001695519 country:US atgff:ConstitutionPipelineLLCMember 2021-01-01 2021-12-31 0001695519 country:US atgff:EatonRapidsGasStorageSystemMember 2022-12-31 0001695519 country:US atgff:EatonRapidsGasStorageSystemMember 2021-12-31 0001695519 country:US atgff:EatonRapidsGasStorageSystemMember 2022-01-01 2022-12-31 0001695519 country:US atgff:EatonRapidsGasStorageSystemMember 2021-01-01 2021-12-31 0001695519 atgff:MountainValleyPipelineLlcMember country:US 2022-12-31 0001695519 atgff:MountainValleyPipelineLlcMember country:US 2021-12-31 0001695519 atgff:MountainValleyPipelineLlcMember country:US 2022-01-01 2022-12-31 0001695519 atgff:MountainValleyPipelineLlcMember country:US 2021-01-01 2021-12-31 0001695519 country:CA atgff:SarniaAirportStoragePoolLpMember 2022-12-31 0001695519 country:CA atgff:SarniaAirportStoragePoolLpMember 2021-12-31 0001695519 country:CA atgff:SarniaAirportStoragePoolLpMember 2022-01-01 2022-12-31 0001695519 country:CA atgff:SarniaAirportStoragePoolLpMember 2021-01-01 2021-12-31 0001695519 country:US atgff:PetrogasTerminalsPennLLCMember 2022-12-31 0001695519 country:US atgff:PetrogasTerminalsPennLLCMember 2021-12-31 0001695519 country:US atgff:PetrogasTerminalsPennLLCMember 2022-01-01 2022-12-31 0001695519 country:US atgff:PetrogasTerminalsPennLLCMember 2021-01-01 2021-12-31 0001695519 country:CA atgff:StrathconaStorageLPMember 2022-01-01 2022-12-31 0001695519 country:CA atgff:StrathconaStorageLPMember 2021-01-01 2021-12-31 0001695519 atgff:PetrogasTerminalsPennLLCMember 2022-07-04 0001695519 atgff:PetrogasTerminalsPennLLCMember 2022-07-05 0001695519 atgff:StrathconaStorageLPMember 2022-07-04 0001695519 atgff:StrathconaStorageLPMember 2022-07-05 0001695519 us-gaap:EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvesteesMember 2022-01-01 2022-12-31 0001695519 us-gaap:EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvesteesMember 2021-01-01 2021-12-31 0001695519 us-gaap:EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvesteesMember 2022-12-31 0001695519 us-gaap:EquityMethodInvestmentNonconsolidatedInvesteeOrGroupOfInvesteesMember 2021-12-31 0001695519 atgff:UnsecuredDemandRevolvingOperatingCreditFacilityMember srt:ParentCompanyMember 2022-12-31 0001695519 atgff:UnsecuredDemandRevolvingOperatingCreditFacilityMember srt:ParentCompanyMember 2021-12-31 0001695519 atgff:UnsecuredBilateralDemandFacilityMember us-gaap:LetterOfCreditMember 2022-12-31 0001695519 atgff:UnsecuredBilateralDemandFacilityMember us-gaap:LetterOfCreditMember 2021-12-31 0001695519 us-gaap:LetterOfCreditMember atgff:DemandLetterCreditFacilityMember 2021-12-31 0001695519 atgff:RevolvingLetterOfCreditFacilityMember 2022-12-31 0001695519 atgff:RevolvingLetterOfCreditFacilityMember 2021-12-31 0001695519 atgff:OperatingFacilityMember 2022-12-31 0001695519 atgff:OperatingFacilityMember 2021-12-31 0001695519 us-gaap:RevolvingCreditFacilityMember atgff:UnsecuredExtendibleRevolvingFacilityDueMay2023Member 2022-12-31 0001695519 us-gaap:RevolvingCreditFacilityMember atgff:UnsecuredExtendibleRevolvingFacilityDueMay2023Member 2021-12-31 0001695519 atgff:UnsecuredExtendibleRevolvingFacilityDue2023Member us-gaap:RevolvingCreditFacilityMember 2022-12-31 0001695519 atgff:UnsecuredExtendibleRevolvingFacilityDue2023Member us-gaap:RevolvingCreditFacilityMember 2021-12-31 0001695519 us-gaap:CommercialPaperMember us-gaap:RevolvingCreditFacilityMember 2022-12-31 0001695519 us-gaap:CommercialPaperMember us-gaap:RevolvingCreditFacilityMember 2021-12-31 0001695519 atgff:TermLoanDue2024Member 2022-12-31 0001695519 atgff:TermLoanDue2024Member 2021-12-31 0001695519 atgff:SeniorUnsecuredNotes2.61DueDec2022Member us-gaap:MediumTermNotesMember 2022-12-31 0001695519 atgff:SeniorUnsecuredNotes2.61DueDec2022Member us-gaap:MediumTermNotesMember 2021-12-31 0001695519 atgff:SeniorUnsecuredNotes3.57DueJun2023Member us-gaap:MediumTermNotesMember 2022-12-31 0001695519 atgff:SeniorUnsecuredNotes3.57DueJun2023Member us-gaap:MediumTermNotesMember 2021-12-31 0001695519 atgff:SeniorUnsecuredNotes4.40DueMar.2024Member us-gaap:MediumTermNotesMember 2022-12-31 0001695519 atgff:SeniorUnsecuredNotes4.40DueMar.2024Member us-gaap:MediumTermNotesMember 2021-12-31 0001695519 atgff:SeniorUnsecuredNotes123DueMarch2024Member us-gaap:MediumTermNotesMember 2022-12-31 0001695519 atgff:SeniorUnsecuredNotes123DueMarch2024Member us-gaap:MediumTermNotesMember 2021-12-31 0001695519 atgff:SeniorUnsecuredNotes3.84DueJan.2025Member us-gaap:MediumTermNotesMember 2022-12-31 0001695519 atgff:SeniorUnsecuredNotes3.84DueJan.2025Member us-gaap:MediumTermNotesMember 2021-12-31 0001695519 atgff:SeniorUnsecuredNotes216DueJune2025Member us-gaap:MediumTermNotesMember 2022-12-31 0001695519 atgff:SeniorUnsecuredNotes216DueJune2025Member us-gaap:MediumTermNotesMember 2021-12-31 0001695519 atgff:SeniorUnsecuredNotes4.12DueApr.2026Member us-gaap:MediumTermNotesMember 2022-12-31 0001695519 atgff:SeniorUnsecuredNotes4.12DueApr.2026Member us-gaap:MediumTermNotesMember 2021-12-31 0001695519 atgff:SeniorUnsecuredNotes217DueMarch2027Member us-gaap:MediumTermNotesMember 2022-12-31 0001695519 atgff:SeniorUnsecuredNotes217DueMarch2027Member us-gaap:MediumTermNotesMember 2021-12-31 0001695519 atgff:SeniorUnsecuredNotes3.98DueOct.2027Member us-gaap:MediumTermNotesMember 2022-12-31 0001695519 atgff:SeniorUnsecuredNotes3.98DueOct.2027Member us-gaap:MediumTermNotesMember 2021-12-31 0001695519 atgff:SeniorUnsecuredNotes208DueMay2028Member us-gaap:MediumTermNotesMember 2022-12-31 0001695519 atgff:SeniorUnsecuredNotes208DueMay2028Member us-gaap:MediumTermNotesMember 2021-12-31 0001695519 atgff:SeniorUnsecuredNotes245DueNovember2030Member us-gaap:MediumTermNotesMember 2022-12-31 0001695519 atgff:SeniorUnsecuredNotes245DueNovember2030Member us-gaap:MediumTermNotesMember 2021-12-31 0001695519 atgff:SeniorUnsecuredNotes5.16DueJan.2044Member us-gaap:MediumTermNotesMember 2022-12-31 0001695519 atgff:SeniorUnsecuredNotes5.16DueJan.2044Member us-gaap:MediumTermNotesMember 2021-12-31 0001695519 atgff:SeniorUnsecuredNotes4.50DueAug.2044Member us-gaap:MediumTermNotesMember 2022-12-31 0001695519 atgff:SeniorUnsecuredNotes4.50DueAug.2044Member us-gaap:MediumTermNotesMember 2021-12-31 0001695519 atgff:SeniorUnsecuredNotes4.99DueOct.2047Member us-gaap:MediumTermNotesMember 2022-12-31 0001695519 atgff:SeniorUnsecuredNotes4.99DueOct.2047Member us-gaap:MediumTermNotesMember 2021-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:SeniorUnsecuredNotes6.55DueMar.2023Member 2022-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:SeniorUnsecuredNotes6.55DueMar.2023Member us-gaap:MediumTermNotesMember 2022-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:SeniorUnsecuredNotes6.55DueMar.2023Member us-gaap:MediumTermNotesMember 2021-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:SeniorUnsecuredNotes5.44DueAug.2025Member 2022-12-31 0001695519 atgff:WglAndWashingtonGasMember us-gaap:MediumTermNotesMember atgff:SeniorUnsecuredNotes5.44DueAug.2025Member 2022-12-31 0001695519 atgff:WglAndWashingtonGasMember us-gaap:MediumTermNotesMember atgff:SeniorUnsecuredNotes5.44DueAug.2025Member 2021-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:SeniorUnsecuredNotes6.62To6.82DueOct.2026Member 2022-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:SeniorUnsecuredNotes6.62To6.82DueOct.2026Member srt:MinimumMember 2022-12-31 0001695519 srt:MaximumMember atgff:WglAndWashingtonGasMember atgff:SeniorUnsecuredNotes6.62To6.82DueOct.2026Member 2022-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:SeniorUnsecuredNotes6.62To6.82DueOct.2026Member us-gaap:MediumTermNotesMember 2022-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:SeniorUnsecuredNotes6.62To6.82DueOct.2026Member us-gaap:MediumTermNotesMember 2021-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:SeniorUnsecuredNotes6.40To6.57DueSep.2027Member 2022-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:SeniorUnsecuredNotes6.40To6.57DueSep.2027Member srt:MinimumMember 2022-12-31 0001695519 srt:MaximumMember atgff:WglAndWashingtonGasMember atgff:SeniorUnsecuredNotes6.40To6.57DueSep.2027Member 2022-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:SeniorUnsecuredNotes6.40To6.57DueSep.2027Member us-gaap:MediumTermNotesMember 2022-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:SeniorUnsecuredNotes6.40To6.57DueSep.2027Member us-gaap:MediumTermNotesMember 2021-12-31 0001695519 atgff:SeniorUnsecuredNotes6.57To6.85DueMar.2028Member atgff:WglAndWashingtonGasMember 2022-12-31 0001695519 atgff:SeniorUnsecuredNotes6.57To6.85DueMar.2028Member atgff:WglAndWashingtonGasMember srt:MinimumMember 2022-12-31 0001695519 srt:MaximumMember atgff:SeniorUnsecuredNotes6.57To6.85DueMar.2028Member atgff:WglAndWashingtonGasMember 2022-12-31 0001695519 atgff:SeniorUnsecuredNotes6.57To6.85DueMar.2028Member atgff:WglAndWashingtonGasMember us-gaap:MediumTermNotesMember 2022-12-31 0001695519 atgff:SeniorUnsecuredNotes6.57To6.85DueMar.2028Member atgff:WglAndWashingtonGasMember us-gaap:MediumTermNotesMember 2021-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:SeniorUnsecuredNotes7.50DueApr.2030Member 2022-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:SeniorUnsecuredNotes7.50DueApr.2030Member us-gaap:MediumTermNotesMember 2022-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:SeniorUnsecuredNotes7.50DueApr.2030Member us-gaap:MediumTermNotesMember 2021-12-31 0001695519 atgff:SeniorUnsecuredNotes5.70to5.78DueMar.2036Member atgff:WglAndWashingtonGasMember 2022-12-31 0001695519 atgff:SeniorUnsecuredNotes5.70to5.78DueMar.2036Member atgff:WglAndWashingtonGasMember srt:MinimumMember 2022-12-31 0001695519 srt:MaximumMember atgff:SeniorUnsecuredNotes5.70to5.78DueMar.2036Member atgff:WglAndWashingtonGasMember 2022-12-31 0001695519 atgff:SeniorUnsecuredNotes5.70to5.78DueMar.2036Member atgff:WglAndWashingtonGasMember us-gaap:MediumTermNotesMember 2022-12-31 0001695519 atgff:SeniorUnsecuredNotes5.70to5.78DueMar.2036Member atgff:WglAndWashingtonGasMember us-gaap:MediumTermNotesMember 2021-12-31 0001695519 atgff:SeniorUnsecuredNotes5.21DueDec.2040Member atgff:WglAndWashingtonGasMember 2022-12-31 0001695519 atgff:SeniorUnsecuredNotes5.21DueDec.2040Member atgff:WglAndWashingtonGasMember us-gaap:MediumTermNotesMember 2022-12-31 0001695519 atgff:SeniorUnsecuredNotes5.21DueDec.2040Member atgff:WglAndWashingtonGasMember us-gaap:MediumTermNotesMember 2021-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:SeniorUnsecuredNotes5.00DueDec.2043Member 2022-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:SeniorUnsecuredNotes5.00DueDec.2043Member us-gaap:MediumTermNotesMember 2022-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:SeniorUnsecuredNotes5.00DueDec.2043Member us-gaap:MediumTermNotesMember 2021-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:SeniorUnsecuredNotes4.22To4.60DueDec.2044Member 2022-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:SeniorUnsecuredNotes4.22To4.60DueDec.2044Member srt:MinimumMember 2022-12-31 0001695519 srt:MaximumMember atgff:WglAndWashingtonGasMember atgff:SeniorUnsecuredNotes4.22To4.60DueDec.2044Member 2022-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:SeniorUnsecuredNotes4.22To4.60DueDec.2044Member us-gaap:MediumTermNotesMember 2022-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:SeniorUnsecuredNotes4.22To4.60DueDec.2044Member us-gaap:MediumTermNotesMember 2021-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:SeniorUnsecuredNotes3.80DueSep.2046Member 2022-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:SeniorUnsecuredNotes3.80DueSep.2046Member us-gaap:MediumTermNotesMember 2022-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:SeniorUnsecuredNotes3.80DueSep.2046Member us-gaap:MediumTermNotesMember 2021-12-31 0001695519 atgff:US300MillionSeniorUnsecured3.65PercentMember atgff:WglAndWashingtonGasMember 2022-12-31 0001695519 atgff:US300MillionSeniorUnsecured3.65PercentMember atgff:WglAndWashingtonGasMember us-gaap:MediumTermNotesMember 2022-12-31 0001695519 atgff:US300MillionSeniorUnsecured3.65PercentMember atgff:WglAndWashingtonGasMember us-gaap:MediumTermNotesMember 2021-12-31 0001695519 atgff:SeniorUnsecuredNotes298DueDecember2051Member atgff:WglAndWashingtonGasMember us-gaap:MediumTermNotesMember 2022-12-31 0001695519 atgff:SeniorUnsecuredNotes298DueDecember2051Member atgff:WglAndWashingtonGasMember us-gaap:MediumTermNotesMember 2021-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:US25MillionSeniorUnsecured525PercentMember us-gaap:MediumTermNotesMember 2022-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:US25MillionSeniorUnsecured525PercentMember us-gaap:MediumTermNotesMember 2021-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:US175MillionSeniorUnsecured533PercentMember us-gaap:MediumTermNotesMember 2022-12-31 0001695519 atgff:WglAndWashingtonGasMember atgff:US175MillionSeniorUnsecured533PercentMember us-gaap:MediumTermNotesMember 2021-12-31 0001695519 us-gaap:LongTermDebtMember atgff:SeniorUnsecuredNotes4.48DueMar.2032Member 2022-12-31 0001695519 us-gaap:LongTermDebtMember atgff:SeniorUnsecuredNotes4.48DueMar.2032Member 2021-12-31 0001695519 us-gaap:LongTermDebtMember atgff:FirstMortgageBonds245DueApril2050Member 2022-12-31 0001695519 us-gaap:LongTermDebtMember atgff:FirstMortgageBonds245DueApril2050Member 2021-12-31 0001695519 us-gaap:LongTermDebtMember atgff:FirstMortgageBonds315DueApril2030Member 2022-12-31 0001695519 us-gaap:LongTermDebtMember atgff:FirstMortgageBonds315DueApril2030Member 2021-12-31 0001695519 us-gaap:LineOfCreditMember us-gaap:RevolvingCreditFacilityMember atgff:UnsecuredExtendibleRevolvingFacilityDueMay2023Member 2022-12-31 0001695519 atgff:ExtendableCommittedRevolvingFacilityMember us-gaap:RevolvingCreditFacilityMember atgff:UnsecuredExtendibleRevolvingFacilityDueMay2023Member 2022-10-01 2022-12-31 0001695519 atgff:ExtendableSideCarLiquidityRevolvingFacilityMember us-gaap:RevolvingCreditFacilityMember atgff:UnsecuredExtendibleRevolvingFacilityDueMay2023Member 2022-12-31 0001695519 atgff:ExtendableSideCarLiquidityRevolvingFacilityMember us-gaap:RevolvingCreditFacilityMember atgff:UnsecuredExtendibleRevolvingFacilityDueMay2023Member 2022-10-01 2022-12-31 0001695519 us-gaap:RevolvingCreditFacilityMember 2022-10-01 2022-12-31 0001695519 us-gaap:RevolvingCreditFacilityMember 2022-12-31 0001695519 us-gaap:RevolvingCreditFacilityMember 2021-12-31 0001695519 us-gaap:LineOfCreditMember us-gaap:RevolvingCreditFacilityMember atgff:UnsecuredExtendibleRevolvingFacilityDueMay2023Member 2022-10-01 2022-12-31 0001695519 atgff:AltagasMember us-gaap:RevolvingCreditFacilityMember 2022-12-31 0001695519 atgff:AltagasMember us-gaap:RevolvingCreditFacilityMember 2022-01-01 2022-12-31 0001695519 us-gaap:LineOfCreditMember atgff:WglHoldingsMember us-gaap:RevolvingCreditFacilityMember 2022-12-31 0001695519 us-gaap:LineOfCreditMember atgff:WglHoldingsMember us-gaap:RevolvingCreditFacilityMember 2021-12-31 0001695519 us-gaap:LineOfCreditMember atgff:WashingtonGasMember us-gaap:RevolvingCreditFacilityMember 2022-12-31 0001695519 us-gaap:LineOfCreditMember atgff:WashingtonGasMember us-gaap:RevolvingCreditFacilityMember 2021-12-31 0001695519 atgff:SemcoMember us-gaap:RevolvingCreditFacilityMember 2022-12-31 0001695519 atgff:SemcoMember us-gaap:RevolvingCreditFacilityMember 2021-12-31 0001695519 atgff:PetrogasEnergyCorporationMember us-gaap:RevolvingCreditFacilityMember 2021-12-31 0001695519 us-gaap:SubordinatedDebtMember atgff:A300MillionSubordinatedNotesSeries1Member 2022-12-31 0001695519 us-gaap:SubordinatedDebtMember atgff:A300MillionSubordinatedNotesSeries1Member 2021-12-31 0001695519 atgff:A250MillionSubordinatedNotesSeries2Member us-gaap:SubordinatedDebtMember 2022-12-31 0001695519 atgff:A250MillionSubordinatedNotesSeries2Member us-gaap:SubordinatedDebtMember 2021-12-31 0001695519 us-gaap:SubordinatedDebtMember 2022-12-31 0001695519 us-gaap:SubordinatedDebtMember 2021-12-31 0001695519 atgff:AltagasMember us-gaap:SubordinatedDebtMember atgff:A300MillionSubordinatedNotesSeries1Member 2022-01-11 0001695519 atgff:A250MillionSubordinatedNotesSeries2Member atgff:AltagasMember us-gaap:SubordinatedDebtMember 2022-08-17 0001695519 atgff:AltagasMember us-gaap:SubordinatedDebtMember 2022-01-01 2022-12-31 0001695519 atgff:AltagasMember us-gaap:SubordinatedDebtMember 2021-01-01 2021-12-31 0001695519 srt:MinimumMember 2022-01-01 2022-12-31 0001695519 srt:MaximumMember 2022-01-01 2022-12-31 0001695519 srt:MinimumMember 2021-01-01 2021-12-31 0001695519 srt:MaximumMember 2021-01-01 2021-12-31 atgff:site 0001695519 srt:MaximumMember 2022-12-31 0001695519 srt:MaximumMember 2021-12-31 0001695519 atgff:DeferredCostOfGasMember 2022-12-31 0001695519 atgff:DeferredCostOfGasMember 2021-12-31 0001695519 atgff:AcceleratedReplacementRecoveryMechanismMember 2022-12-31 0001695519 atgff:AcceleratedReplacementRecoveryMechanismMember 2021-12-31 0001695519 atgff:EnergyOptimizationCostsMember 2022-12-31 0001695519 atgff:EnergyOptimizationCostsMember 2021-12-31 0001695519 atgff:VirginiaAndMarylandRevenueNormalizationMember 2022-12-31 0001695519 atgff:VirginiaAndMarylandRevenueNormalizationMember 2021-12-31 0001695519 us-gaap:DeferredProjectCostsMember 2022-12-31 0001695519 us-gaap:DeferredProjectCostsMember 2021-12-31 0001695519 srt:MinimumMember us-gaap:DeferredProjectCostsMember 2022-01-01 2022-12-31 0001695519 srt:MaximumMember us-gaap:DeferredProjectCostsMember 2022-01-01 2022-12-31 0001695519 us-gaap:PensionAndOtherPostretirementPlansCostsMember 2022-12-31 0001695519 us-gaap:PensionAndOtherPostretirementPlansCostsMember 2021-12-31 0001695519 us-gaap:PensionAndOtherPostretirementPlansCostsMember srt:MinimumMember 2022-01-01 2022-12-31 0001695519 us-gaap:PensionAndOtherPostretirementPlansCostsMember srt:MaximumMember 2022-01-01 2022-12-31 0001695519 atgff:FutureRecoveryOfNonRetirementEmployeeBenefitsMember 2022-12-31 0001695519 atgff:FutureRecoveryOfNonRetirementEmployeeBenefitsMember 2021-12-31 0001695519 atgff:DeferredEnvironmentalCostsMember 2022-12-31 0001695519 atgff:DeferredEnvironmentalCostsMember 2021-12-31 0001695519 us-gaap:LossOnReacquiredDebtMember 2022-12-31 0001695519 us-gaap:LossOnReacquiredDebtMember 2021-12-31 0001695519 us-gaap:DeferredIncomeTaxChargesMember 2022-12-31 0001695519 us-gaap:DeferredIncomeTaxChargesMember 2021-12-31 0001695519 atgff:EnergyEfficiencyProgramMember 2022-12-31 0001695519 atgff:EnergyEfficiencyProgramMember 2021-12-31 0001695519 atgff:COVID19CostsMember 2022-12-31 0001695519 atgff:COVID19CostsMember 2021-12-31 0001695519 atgff:OtherRegulatoryAssetMember 2022-12-31 0001695519 atgff:OtherRegulatoryAssetMember 2021-12-31 0001695519 atgff:DeferredCostOfGasLiabilityMember 2022-12-31 0001695519 atgff:DeferredCostOfGasLiabilityMember 2021-12-31 0001695519 atgff:RefundableTaxCreditMember 2022-12-31 0001695519 atgff:RefundableTaxCreditMember 2021-12-31 0001695519 atgff:FederalIncomeTaxRateChangeMember 2022-12-31 0001695519 atgff:FederalIncomeTaxRateChangeMember 2021-12-31 0001695519 atgff:VirginiaRateRefundMember 2022-12-31 0001695519 atgff:VirginiaRateRefundMember 2021-12-31 0001695519 atgff:InterruptibleSharingMember 2022-12-31 0001695519 atgff:InterruptibleSharingMember 2021-12-31 0001695519 atgff:VirginiaAndMarylandRevenueNormalizationMember 2022-12-31 0001695519 atgff:VirginiaAndMarylandRevenueNormalizationMember 2021-12-31 0001695519 atgff:VirginiaCoronavirusReliefFundMember 2022-12-31 0001695519 atgff:VirginiaCoronavirusReliefFundMember 2021-12-31 0001695519 atgff:OtherRegulatoryLiabilityMember 2022-12-31 0001695519 atgff:OtherRegulatoryLiabilityMember 2021-12-31 0001695519 us-gaap:PensionAndOtherPostretirementPlansCostsMember 2022-12-31 0001695519 us-gaap:PensionAndOtherPostretirementPlansCostsMember 2021-12-31 0001695519 us-gaap:RemovalCostsMember 2022-12-31 0001695519 us-gaap:RemovalCostsMember 2021-12-31 0001695519 atgff:DeferredLossOnReacquiredDebtMember 2022-12-31 0001695519 atgff:DeferredLossOnReacquiredDebtMember 2021-12-31 0001695519 atgff:DeferredLossOnReacquiredDebtMember 2022-01-01 2022-12-31 0001695519 atgff:DeferredLossOnReacquiredDebtMember 2021-01-01 2021-12-31 0001695519 us-gaap:LossOnReacquiredDebtMember 2021-01-01 2021-12-31 0001695519 us-gaap:AccumulatedDefinedBenefitPlansAdjustmentMember 2021-12-31 0001695519 us-gaap:AccumulatedGainLossNetCashFlowHedgeParentMember 2021-12-31 0001695519 us-gaap:AccumulatedTranslationAdjustmentMember 2021-12-31 0001695519 us-gaap:AccumulatedDefinedBenefitPlansAdjustmentMember 2022-01-01 2022-12-31 0001695519 us-gaap:AccumulatedGainLossNetCashFlowHedgeParentMember 2022-01-01 2022-12-31 0001695519 us-gaap:AccumulatedTranslationAdjustmentMember 2022-01-01 2022-12-31 0001695519 us-gaap:AccumulatedDefinedBenefitPlansAdjustmentMember 2022-12-31 0001695519 us-gaap:AccumulatedGainLossNetCashFlowHedgeParentMember 2022-12-31 0001695519 us-gaap:AccumulatedTranslationAdjustmentMember 2022-12-31 0001695519 us-gaap:AccumulatedDefinedBenefitPlansAdjustmentMember 2020-12-31 0001695519 us-gaap:AccumulatedGainLossNetCashFlowHedgeParentMember 2020-12-31 0001695519 us-gaap:AccumulatedTranslationAdjustmentMember 2020-12-31 0001695519 us-gaap:AccumulatedDefinedBenefitPlansAdjustmentMember 2021-01-01 2021-12-31 0001695519 us-gaap:AccumulatedGainLossNetCashFlowHedgeParentMember 2021-01-01 2021-12-31 0001695519 us-gaap:AccumulatedTranslationAdjustmentMember 2021-01-01 2021-12-31 0001695519 us-gaap:PortionAtOtherThanFairValueFairValueDisclosureMember atgff:FairValueThroughNetIncomeMember 2022-12-31 0001695519 us-gaap:EstimateOfFairValueFairValueDisclosureMember us-gaap:FairValueInputsLevel1Member atgff:FairValueThroughNetIncomeMember 2022-12-31 0001695519 us-gaap:EstimateOfFairValueFairValueDisclosureMember us-gaap:FairValueInputsLevel2Member atgff:FairValueThroughNetIncomeMember 2022-12-31 0001695519 us-gaap:EstimateOfFairValueFairValueDisclosureMember us-gaap:FairValueInputsLevel3Member atgff:FairValueThroughNetIncomeMember 2022-12-31 0001695519 us-gaap:EstimateOfFairValueFairValueDisclosureMember atgff:FairValueThroughNetIncomeMember 2022-12-31 0001695519 us-gaap:PortionAtOtherThanFairValueFairValueDisclosureMember atgff:FairValueThroughRegulatoryAssetsLiabilitiesMember 2022-12-31 0001695519 us-gaap:EstimateOfFairValueFairValueDisclosureMember us-gaap:FairValueInputsLevel1Member atgff:FairValueThroughRegulatoryAssetsLiabilitiesMember 2022-12-31 0001695519 us-gaap:EstimateOfFairValueFairValueDisclosureMember atgff:FairValueThroughRegulatoryAssetsLiabilitiesMember us-gaap:FairValueInputsLevel2Member 2022-12-31 0001695519 us-gaap:EstimateOfFairValueFairValueDisclosureMember us-gaap:FairValueInputsLevel3Member atgff:FairValueThroughRegulatoryAssetsLiabilitiesMember 2022-12-31 0001695519 us-gaap:EstimateOfFairValueFairValueDisclosureMember atgff:FairValueThroughRegulatoryAssetsLiabilitiesMember 2022-12-31 0001695519 us-gaap:PortionAtOtherThanFairValueFairValueDisclosureMember 2022-12-31 0001695519 us-gaap:EstimateOfFairValueFairValueDisclosureMember us-gaap:FairValueInputsLevel1Member 2022-12-31 0001695519 us-gaap:EstimateOfFairValueFairValueDisclosureMember us-gaap:FairValueInputsLevel2Member 2022-12-31 0001695519 us-gaap:EstimateOfFairValueFairValueDisclosureMember us-gaap:FairValueInputsLevel3Member 2022-12-31 0001695519 us-gaap:EstimateOfFairValueFairValueDisclosureMember 2022-12-31 0001695519 us-gaap:OtherCurrentLiabilitiesMember 2022-12-31 0001695519 us-gaap:PortionAtOtherThanFairValueFairValueDisclosureMember atgff:FairValueThroughNetIncomeMember 2021-12-31 0001695519 us-gaap:EstimateOfFairValueFairValueDisclosureMember us-gaap:FairValueInputsLevel1Member atgff:FairValueThroughNetIncomeMember 2021-12-31 0001695519 us-gaap:EstimateOfFairValueFairValueDisclosureMember us-gaap:FairValueInputsLevel2Member atgff:FairValueThroughNetIncomeMember 2021-12-31 0001695519 us-gaap:EstimateOfFairValueFairValueDisclosureMember us-gaap:FairValueInputsLevel3Member atgff:FairValueThroughNetIncomeMember 2021-12-31 0001695519 us-gaap:EstimateOfFairValueFairValueDisclosureMember atgff:FairValueThroughNetIncomeMember 2021-12-31 0001695519 us-gaap:PortionAtOtherThanFairValueFairValueDisclosureMember atgff:FairValueThroughRegulatoryAssetsLiabilitiesMember 2021-12-31 0001695519 us-gaap:EstimateOfFairValueFairValueDisclosureMember us-gaap:FairValueInputsLevel1Member atgff:FairValueThroughRegulatoryAssetsLiabilitiesMember 2021-12-31 0001695519 us-gaap:EstimateOfFairValueFairValueDisclosureMember atgff:FairValueThroughRegulatoryAssetsLiabilitiesMember us-gaap:FairValueInputsLevel2Member 2021-12-31 0001695519 us-gaap:EstimateOfFairValueFairValueDisclosureMember us-gaap:FairValueInputsLevel3Member atgff:FairValueThroughRegulatoryAssetsLiabilitiesMember 2021-12-31 0001695519 us-gaap:EstimateOfFairValueFairValueDisclosureMember atgff:FairValueThroughRegulatoryAssetsLiabilitiesMember 2021-12-31 0001695519 us-gaap:PortionAtOtherThanFairValueFairValueDisclosureMember 2021-12-31 0001695519 us-gaap:EstimateOfFairValueFairValueDisclosureMember us-gaap:FairValueInputsLevel1Member 2021-12-31 0001695519 us-gaap:EstimateOfFairValueFairValueDisclosureMember us-gaap:FairValueInputsLevel2Member 2021-12-31 0001695519 us-gaap:EstimateOfFairValueFairValueDisclosureMember us-gaap:FairValueInputsLevel3Member 2021-12-31 0001695519 us-gaap:EstimateOfFairValueFairValueDisclosureMember 2021-12-31 0001695519 srt:NaturalGasReservesMember us-gaap:ValuationTechniqueDiscountedCashFlowMember 2022-12-31 0001695519 srt:NaturalGasReservesMember us-gaap:ValuationTechniqueDiscountedCashFlowMember srt:MinimumMember 2022-12-31 iso4217:CAD atgff:dekatherm 0001695519 srt:NaturalGasReservesMember us-gaap:ValuationTechniqueDiscountedCashFlowMember srt:MaximumMember 2022-12-31 0001695519 srt:NaturalGasReservesMember us-gaap:ValuationTechniqueOptionPricingModelMember 2022-12-31 0001695519 srt:NaturalGasReservesMember us-gaap:ValuationTechniqueOptionPricingModelMember srt:MinimumMember 2022-12-31 0001695519 srt:NaturalGasReservesMember srt:MaximumMember us-gaap:ValuationTechniqueOptionPricingModelMember 2022-12-31 0001695519 srt:NaturalGasReservesMember us-gaap:ValuationTechniqueOptionPricingModelMember srt:MinimumMember 2022-01-01 2022-12-31 0001695519 srt:NaturalGasReservesMember srt:MaximumMember us-gaap:ValuationTechniqueOptionPricingModelMember 2022-01-01 2022-12-31 0001695519 srt:NaturalGasReservesMember us-gaap:ValuationTechniqueOptionPricingModelMember 2022-01-01 2022-12-31 0001695519 us-gaap:ValuationTechniqueDiscountedCashFlowMember atgff:ElectricityFinancialInstrumentsMember 2022-12-31 0001695519 us-gaap:ValuationTechniqueDiscountedCashFlowMember atgff:ElectricityFinancialInstrumentsMember srt:MinimumMember 2022-12-31 iso4217:CAD utr:MWh 0001695519 us-gaap:ValuationTechniqueDiscountedCashFlowMember srt:MaximumMember atgff:ElectricityFinancialInstrumentsMember 2022-12-31 0001695519 srt:NaturalGasReservesMember 2021-12-31 0001695519 atgff:ElectricityFinancialInstrumentsMember 2021-12-31 0001695519 srt:NaturalGasReservesMember 2020-12-31 0001695519 atgff:ElectricityFinancialInstrumentsMember 2020-12-31 0001695519 srt:NaturalGasReservesMember 2022-01-01 2022-12-31 0001695519 atgff:ElectricityFinancialInstrumentsMember 2022-01-01 2022-12-31 0001695519 srt:NaturalGasReservesMember 2021-01-01 2021-12-31 0001695519 atgff:ElectricityFinancialInstrumentsMember 2021-01-01 2021-12-31 0001695519 srt:NaturalGasReservesMember 2022-12-31 0001695519 atgff:ElectricityFinancialInstrumentsMember 2022-12-31 0001695519 us-gaap:CommodityContractMember us-gaap:TradingRevenueMember 2022-01-01 2022-12-31 0001695519 us-gaap:CommodityContractMember us-gaap:TradingRevenueMember 2021-01-01 2021-12-31 0001695519 us-gaap:CostOfSalesMember us-gaap:CommodityContractMember 2022-01-01 2022-12-31 0001695519 us-gaap:CostOfSalesMember us-gaap:CommodityContractMember 2021-01-01 2021-12-31 0001695519 atgff:NaturalGasRiskManagementContractsMember 2022-01-01 2022-12-31 0001695519 atgff:NaturalGasRiskManagementContractsMember 2021-01-01 2021-12-31 0001695519 atgff:StorageOptimizationContractsMember 2022-01-01 2022-12-31 0001695519 atgff:StorageOptimizationContractsMember 2021-01-01 2021-12-31 0001695519 srt:CrudeOilAndNGLPerBarrelMember 2022-01-01 2022-12-31 0001695519 srt:CrudeOilAndNGLPerBarrelMember 2021-01-01 2021-12-31 0001695519 atgff:NaturalGasLiquidsFracSpreadContractsMember 2022-01-01 2022-12-31 0001695519 atgff:NaturalGasLiquidsFracSpreadContractsMember 2021-01-01 2021-12-31 0001695519 atgff:PowerRiskManagementContractsMember 2022-01-01 2022-12-31 0001695519 atgff:PowerRiskManagementContractsMember 2021-01-01 2021-12-31 0001695519 us-gaap:ForeignExchangeContractMember 2022-01-01 2022-12-31 0001695519 us-gaap:ForeignExchangeContractMember 2021-01-01 2021-12-31 0001695519 atgff:NaturalGasRiskManagementContractsMember 2022-12-31 0001695519 atgff:EnergyExportsMember 2022-12-31 0001695519 srt:CrudeOilAndNGLPerBarrelMember 2022-12-31 0001695519 atgff:NaturalGasLiquidsFracSpreadContractsMember 2022-12-31 0001695519 atgff:PowerRiskManagementContractsMember 2022-12-31 0001695519 atgff:RiskManagementContractsMember 2022-12-31 0001695519 atgff:NaturalGasRiskManagementContractsMember 2021-12-31 0001695519 atgff:EnergyExportsMember 2021-12-31 0001695519 atgff:NaturalGasLiquidsFracSpreadContractsMember 2021-12-31 0001695519 atgff:PowerRiskManagementContractsMember 2021-12-31 0001695519 atgff:RiskManagementContractsMember 2021-12-31 0001695519 srt:CrudeOilAndNGLPerBarrelMember 2021-12-31 0001695519 atgff:SalesContractsMember atgff:NaturalGasRiskManagementContractsMember srt:MinimumMember 2022-12-31 iso4217:CAD atgff:gigajoule 0001695519 atgff:SalesContractsMember srt:MaximumMember atgff:NaturalGasRiskManagementContractsMember 2022-12-31 0001695519 atgff:SalesContractsMember atgff:NaturalGasRiskManagementContractsMember srt:MinimumMember 2022-01-01 2022-12-31 0001695519 atgff:SalesContractsMember srt:MaximumMember atgff:NaturalGasRiskManagementContractsMember 2022-01-01 2022-12-31 0001695519 atgff:SalesContractsMember atgff:NaturalGasRiskManagementContractsMember 2022-01-01 2022-12-31 utr:kJ 0001695519 atgff:SalesContractsMember atgff:NaturalGasRiskManagementContractsMember 2022-12-31 0001695519 atgff:PurchaseContractsMember atgff:NaturalGasRiskManagementContractsMember srt:MinimumMember 2022-12-31 0001695519 srt:MaximumMember atgff:PurchaseContractsMember atgff:NaturalGasRiskManagementContractsMember 2022-12-31 0001695519 atgff:PurchaseContractsMember atgff:NaturalGasRiskManagementContractsMember srt:MinimumMember 2022-01-01 2022-12-31 0001695519 srt:MaximumMember atgff:PurchaseContractsMember atgff:NaturalGasRiskManagementContractsMember 2022-01-01 2022-12-31 0001695519 atgff:PurchaseContractsMember atgff:NaturalGasRiskManagementContractsMember 2022-01-01 2022-12-31 0001695519 atgff:PurchaseContractsMember atgff:NaturalGasRiskManagementContractsMember 2022-12-31 0001695519 atgff:NaturalGasRiskManagementContractsMember srt:MinimumMember us-gaap:SwapMember 2022-12-31 0001695519 srt:MaximumMember atgff:NaturalGasRiskManagementContractsMember us-gaap:SwapMember 2022-12-31 0001695519 atgff:NaturalGasRiskManagementContractsMember srt:MinimumMember us-gaap:SwapMember 2022-01-01 2022-12-31 0001695519 srt:MaximumMember atgff:NaturalGasRiskManagementContractsMember us-gaap:SwapMember 2022-01-01 2022-12-31 0001695519 atgff:NaturalGasRiskManagementContractsMember us-gaap:SwapMember 2022-01-01 2022-12-31 0001695519 atgff:NaturalGasRiskManagementContractsMember us-gaap:SwapMember 2022-12-31 0001695519 atgff:SalesContractsMember atgff:NaturalGasRiskManagementContractsMember srt:MinimumMember 2021-12-31 0001695519 atgff:SalesContractsMember srt:MaximumMember atgff:NaturalGasRiskManagementContractsMember 2021-12-31 0001695519 atgff:SalesContractsMember atgff:NaturalGasRiskManagementContractsMember srt:MinimumMember 2021-01-01 2021-12-31 0001695519 atgff:SalesContractsMember srt:MaximumMember atgff:NaturalGasRiskManagementContractsMember 2021-01-01 2021-12-31 0001695519 atgff:SalesContractsMember atgff:NaturalGasRiskManagementContractsMember 2021-01-01 2021-12-31 0001695519 atgff:SalesContractsMember atgff:NaturalGasRiskManagementContractsMember 2021-12-31 0001695519 atgff:PurchaseContractsMember atgff:NaturalGasRiskManagementContractsMember srt:MinimumMember 2021-12-31 0001695519 srt:MaximumMember atgff:PurchaseContractsMember atgff:NaturalGasRiskManagementContractsMember 2021-12-31 0001695519 atgff:PurchaseContractsMember atgff:NaturalGasRiskManagementContractsMember srt:MinimumMember 2021-01-01 2021-12-31 0001695519 srt:MaximumMember atgff:PurchaseContractsMember atgff:NaturalGasRiskManagementContractsMember 2021-01-01 2021-12-31 0001695519 atgff:PurchaseContractsMember atgff:NaturalGasRiskManagementContractsMember 2021-01-01 2021-12-31 0001695519 atgff:PurchaseContractsMember atgff:NaturalGasRiskManagementContractsMember 2021-12-31 0001695519 atgff:NaturalGasRiskManagementContractsMember srt:MinimumMember us-gaap:SwapMember 2021-12-31 0001695519 srt:MaximumMember atgff:NaturalGasRiskManagementContractsMember us-gaap:SwapMember 2021-12-31 0001695519 atgff:NaturalGasRiskManagementContractsMember srt:MinimumMember us-gaap:SwapMember 2021-01-01 2021-12-31 0001695519 srt:MaximumMember atgff:NaturalGasRiskManagementContractsMember us-gaap:SwapMember 2021-01-01 2021-12-31 0001695519 atgff:NaturalGasRiskManagementContractsMember us-gaap:SwapMember 2021-01-01 2021-12-31 0001695519 atgff:NaturalGasRiskManagementContractsMember us-gaap:SwapMember 2021-12-31 0001695519 atgff:MountainValleyPipelineLlcMember atgff:PurchaseContractsMember atgff:NaturalGasRiskManagementContractsMember 2022-01-01 2022-12-31 utr:GJ 0001695519 srt:CrudeOilAndNGLPerBarrelMember srt:MinimumMember us-gaap:SwapMember 2022-12-31 0001695519 srt:MaximumMember srt:CrudeOilAndNGLPerBarrelMember us-gaap:SwapMember 2022-12-31 0001695519 srt:CrudeOilAndNGLPerBarrelMember srt:MinimumMember us-gaap:SwapMember 2022-01-01 2022-12-31 0001695519 srt:MaximumMember srt:CrudeOilAndNGLPerBarrelMember us-gaap:SwapMember 2022-01-01 2022-12-31 0001695519 srt:CrudeOilAndNGLPerBarrelMember us-gaap:SwapMember 2022-01-01 2022-12-31 utr:bbl 0001695519 srt:CrudeOilAndNGLPerBarrelMember us-gaap:SwapMember 2022-12-31 0001695519 srt:CrudeOilAndNGLPerBarrelMember srt:MinimumMember us-gaap:SwapMember 2021-12-31 0001695519 srt:MaximumMember srt:CrudeOilAndNGLPerBarrelMember us-gaap:SwapMember 2021-12-31 0001695519 srt:CrudeOilAndNGLPerBarrelMember srt:MinimumMember us-gaap:SwapMember 2021-01-01 2021-12-31 0001695519 srt:MaximumMember srt:CrudeOilAndNGLPerBarrelMember us-gaap:SwapMember 2021-01-01 2021-12-31 0001695519 srt:CrudeOilAndNGLPerBarrelMember us-gaap:SwapMember 2021-01-01 2021-12-31 0001695519 srt:CrudeOilAndNGLPerBarrelMember us-gaap:SwapMember 2021-12-31 0001695519 srt:MaximumMember atgff:EnergyExportsMember 2022-12-31 iso4217:CAD atgff:barrel 0001695519 atgff:EnergyExportsMember srt:MinimumMember 2022-01-01 2022-12-31 0001695519 srt:MaximumMember atgff:EnergyExportsMember 2022-01-01 2022-12-31 0001695519 atgff:EnergyExportsMember 2022-01-01 2022-12-31 0001695519 atgff:EnergyExportsMember srt:MinimumMember atgff:PropaneAndButaneSwapsMember 2022-12-31 0001695519 srt:MaximumMember atgff:EnergyExportsMember atgff:PropaneAndButaneSwapsMember 2022-12-31 0001695519 atgff:EnergyExportsMember srt:MinimumMember atgff:PropaneAndButaneSwapsMember 2022-01-01 2022-12-31 0001695519 srt:MaximumMember atgff:EnergyExportsMember atgff:PropaneAndButaneSwapsMember 2022-01-01 2022-12-31 0001695519 atgff:EnergyExportsMember atgff:PropaneAndButaneSwapsMember 2022-01-01 2022-12-31 0001695519 atgff:EnergyExportsMember atgff:PropaneAndButaneSwapsMember 2022-12-31 0001695519 atgff:EnergyExportsMember srt:MinimumMember atgff:PropaneAndButaneSwapsMember 2021-12-31 0001695519 srt:MaximumMember atgff:EnergyExportsMember atgff:PropaneAndButaneSwapsMember 2021-12-31 0001695519 atgff:EnergyExportsMember srt:MinimumMember atgff:PropaneAndButaneSwapsMember 2021-01-01 2021-12-31 0001695519 srt:MaximumMember atgff:EnergyExportsMember atgff:PropaneAndButaneSwapsMember 2021-01-01 2021-12-31 0001695519 atgff:EnergyExportsMember atgff:PropaneAndButaneSwapsMember 2021-01-01 2021-12-31 0001695519 atgff:EnergyExportsMember atgff:PropaneAndButaneSwapsMember 2021-12-31 0001695519 us-gaap:PublicUtilitiesInventoryPropaneMember srt:MinimumMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2022-12-31 0001695519 us-gaap:PublicUtilitiesInventoryPropaneMember srt:MaximumMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2022-12-31 0001695519 us-gaap:PublicUtilitiesInventoryPropaneMember srt:MinimumMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2022-01-01 2022-12-31 0001695519 us-gaap:PublicUtilitiesInventoryPropaneMember srt:MaximumMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2022-01-01 2022-12-31 0001695519 us-gaap:PublicUtilitiesInventoryPropaneMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2022-01-01 2022-12-31 0001695519 us-gaap:PublicUtilitiesInventoryPropaneMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2022-12-31 0001695519 srt:CrudeOilMember srt:MinimumMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2022-12-31 0001695519 srt:MaximumMember srt:CrudeOilMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2022-12-31 0001695519 srt:CrudeOilMember srt:MinimumMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2022-01-01 2022-12-31 0001695519 srt:MaximumMember srt:CrudeOilMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2022-01-01 2022-12-31 0001695519 srt:CrudeOilMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2022-01-01 2022-12-31 0001695519 srt:CrudeOilMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2022-12-31 0001695519 srt:MinimumMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember srt:NaturalGasReservesMember 2022-12-31 0001695519 srt:MaximumMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember srt:NaturalGasReservesMember 2022-12-31 0001695519 srt:MinimumMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember srt:NaturalGasReservesMember 2022-01-01 2022-12-31 0001695519 srt:MaximumMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember srt:NaturalGasReservesMember 2022-01-01 2022-12-31 0001695519 atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember srt:NaturalGasReservesMember 2022-01-01 2022-12-31 0001695519 atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember srt:NaturalGasReservesMember 2022-12-31 0001695519 us-gaap:PublicUtilitiesInventoryPropaneMember srt:MinimumMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2021-12-31 0001695519 us-gaap:PublicUtilitiesInventoryPropaneMember srt:MaximumMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2021-12-31 0001695519 us-gaap:PublicUtilitiesInventoryPropaneMember srt:MinimumMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2021-01-01 2021-12-31 0001695519 us-gaap:PublicUtilitiesInventoryPropaneMember srt:MaximumMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2021-01-01 2021-12-31 0001695519 us-gaap:PublicUtilitiesInventoryPropaneMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2021-01-01 2021-12-31 0001695519 us-gaap:PublicUtilitiesInventoryPropaneMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2021-12-31 0001695519 atgff:ButaneMember srt:MinimumMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2021-12-31 0001695519 srt:MaximumMember atgff:ButaneMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2021-12-31 0001695519 atgff:ButaneMember srt:MinimumMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2021-01-01 2021-12-31 0001695519 srt:MaximumMember atgff:ButaneMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2021-01-01 2021-12-31 0001695519 atgff:ButaneMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2021-01-01 2021-12-31 0001695519 atgff:ButaneMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2021-12-31 0001695519 srt:CrudeOilMember srt:MinimumMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2021-12-31 0001695519 srt:MaximumMember srt:CrudeOilMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2021-12-31 0001695519 srt:CrudeOilMember srt:MinimumMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2021-01-01 2021-12-31 0001695519 srt:MaximumMember srt:CrudeOilMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2021-01-01 2021-12-31 0001695519 srt:CrudeOilMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2021-01-01 2021-12-31 0001695519 srt:CrudeOilMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember 2021-12-31 0001695519 srt:MinimumMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember srt:NaturalGasReservesMember 2021-12-31 0001695519 srt:MaximumMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember srt:NaturalGasReservesMember 2021-12-31 0001695519 srt:MinimumMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember srt:NaturalGasReservesMember 2021-01-01 2021-12-31 0001695519 srt:MaximumMember atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember srt:NaturalGasReservesMember 2021-01-01 2021-12-31 0001695519 atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember srt:NaturalGasReservesMember 2021-01-01 2021-12-31 0001695519 atgff:NaturalGasLiquidsFracSpreadContractsMember us-gaap:SwapMember srt:NaturalGasReservesMember 2021-12-31 0001695519 atgff:SalesContractsMember atgff:PowerRiskManagementContractsMember srt:MinimumMember 2022-12-31 0001695519 atgff:SalesContractsMember srt:MaximumMember atgff:PowerRiskManagementContractsMember 2022-12-31 0001695519 atgff:SalesContractsMember atgff:PowerRiskManagementContractsMember srt:MinimumMember 2022-01-01 2022-12-31 0001695519 atgff:SalesContractsMember srt:MaximumMember atgff:PowerRiskManagementContractsMember 2022-01-01 2022-12-31 0001695519 atgff:SalesContractsMember atgff:PowerRiskManagementContractsMember 2022-01-01 2022-12-31 utr:MWh 0001695519 atgff:SalesContractsMember atgff:PowerRiskManagementContractsMember 2022-12-31 0001695519 atgff:PurchaseContractsMember atgff:PowerRiskManagementContractsMember srt:MinimumMember 2022-12-31 0001695519 srt:MaximumMember atgff:PurchaseContractsMember atgff:PowerRiskManagementContractsMember 2022-12-31 0001695519 atgff:PurchaseContractsMember atgff:PowerRiskManagementContractsMember srt:MinimumMember 2022-01-01 2022-12-31 0001695519 srt:MaximumMember atgff:PurchaseContractsMember atgff:PowerRiskManagementContractsMember 2022-01-01 2022-12-31 0001695519 atgff:PurchaseContractsMember atgff:PowerRiskManagementContractsMember 2022-01-01 2022-12-31 0001695519 atgff:PurchaseContractsMember atgff:PowerRiskManagementContractsMember 2022-12-31 0001695519 atgff:PowerRiskManagementContractsMember srt:MinimumMember us-gaap:SwapMember 2022-12-31 0001695519 srt:MaximumMember atgff:PowerRiskManagementContractsMember us-gaap:SwapMember 2022-12-31 0001695519 atgff:PowerRiskManagementContractsMember srt:MinimumMember us-gaap:SwapMember 2022-01-01 2022-12-31 0001695519 srt:MaximumMember atgff:PowerRiskManagementContractsMember us-gaap:SwapMember 2022-01-01 2022-12-31 0001695519 atgff:PowerRiskManagementContractsMember us-gaap:SwapMember 2022-01-01 2022-12-31 0001695519 atgff:PowerRiskManagementContractsMember us-gaap:SwapMember 2022-12-31 0001695519 atgff:SalesContractsMember atgff:PowerRiskManagementContractsMember srt:MinimumMember 2021-12-31 0001695519 atgff:SalesContractsMember srt:MaximumMember atgff:PowerRiskManagementContractsMember 2021-12-31 0001695519 atgff:SalesContractsMember atgff:PowerRiskManagementContractsMember srt:MinimumMember 2021-01-01 2021-12-31 0001695519 atgff:SalesContractsMember srt:MaximumMember atgff:PowerRiskManagementContractsMember 2021-01-01 2021-12-31 0001695519 atgff:SalesContractsMember atgff:PowerRiskManagementContractsMember 2021-01-01 2021-12-31 0001695519 atgff:SalesContractsMember atgff:PowerRiskManagementContractsMember 2021-12-31 0001695519 atgff:PurchaseContractsMember atgff:PowerRiskManagementContractsMember srt:MinimumMember 2021-12-31 0001695519 srt:MaximumMember atgff:PurchaseContractsMember atgff:PowerRiskManagementContractsMember 2021-12-31 0001695519 atgff:PurchaseContractsMember atgff:PowerRiskManagementContractsMember srt:MinimumMember 2021-01-01 2021-12-31 0001695519 srt:MaximumMember atgff:PurchaseContractsMember atgff:PowerRiskManagementContractsMember 2021-01-01 2021-12-31 0001695519 atgff:PurchaseContractsMember atgff:PowerRiskManagementContractsMember 2021-01-01 2021-12-31 0001695519 atgff:PurchaseContractsMember atgff:PowerRiskManagementContractsMember 2021-12-31 0001695519 atgff:PowerRiskManagementContractsMember srt:MinimumMember us-gaap:SwapMember 2021-12-31 0001695519 srt:MaximumMember atgff:PowerRiskManagementContractsMember us-gaap:SwapMember 2021-12-31 0001695519 atgff:PowerRiskManagementContractsMember srt:MinimumMember us-gaap:SwapMember 2021-01-01 2021-12-31 0001695519 srt:MaximumMember atgff:PowerRiskManagementContractsMember us-gaap:SwapMember 2021-01-01 2021-12-31 0001695519 atgff:PowerRiskManagementContractsMember us-gaap:SwapMember 2021-01-01 2021-12-31 0001695519 atgff:PowerRiskManagementContractsMember us-gaap:SwapMember 2021-12-31 0001695519 atgff:PjmPowerPriceMember 2022-01-01 2022-12-31 iso4217:USD utr:MWh 0001695519 atgff:NymexNaturalGasPriceMember 2022-01-01 2022-12-31 iso4217:USD atgff:gigajoule 0001695519 us-gaap:PublicUtilitiesInventoryPropaneMember atgff:EnergyExportsMember 2022-01-01 2022-12-31 0001695519 atgff:BalticFreightsMember us-gaap:PublicUtilitiesInventoryPropaneMember 2022-01-01 2022-12-31 0001695519 atgff:BalticFreightsMember 2022-01-01 2022-12-31 0001695519 us-gaap:PublicUtilitiesInventoryPropaneMember atgff:NaturalGasLiquidsFracSpreadContractsMember 2022-01-01 2022-12-31 0001695519 atgff:NaturalGasLiquidsFracSpreadContractsMember srt:NaturalGasReservesMember 2022-01-01 2022-12-31 0001695519 us-gaap:NetInvestmentHedgingMember 2022-12-31 0001695519 us-gaap:NetInvestmentHedgingMember 2021-12-31 0001695519 us-gaap:ForeignExchangeForwardMember us-gaap:SwapMember 2021-12-31 0001695519 us-gaap:ForeignExchangeForwardMember 2022-01-01 2022-12-31 0001695519 us-gaap:ForeignExchangeForwardMember 2021-01-01 2021-12-31 0001695519 us-gaap:InterestRateSwapMember 2022-12-31 0001695519 us-gaap:InterestRateSwapMember 2021-12-31 0001695519 atgff:WeatherRelatedInstrumentsMember 2022-01-01 2022-12-31 0001695519 atgff:WeatherRelatedInstrumentsMember 2021-01-01 2021-12-31 0001695519 us-gaap:TradeAccountsReceivableMember 2022-12-31 0001695519 us-gaap:TradeAccountsReceivableMember us-gaap:FinancingReceivables1To29DaysPastDueMember 2022-12-31 0001695519 us-gaap:TradeAccountsReceivableMember us-gaap:FinancingReceivables30To59DaysPastDueMember 2022-12-31 0001695519 us-gaap:FinancingReceivables60To89DaysPastDueMember us-gaap:TradeAccountsReceivableMember 2022-12-31 0001695519 us-gaap:FinancingReceivablesEqualToGreaterThan90DaysPastDueMember us-gaap:TradeAccountsReceivableMember 2022-12-31 0001695519 atgff:OtherAccountsReceivablesMember 2022-12-31 0001695519 atgff:OtherAccountsReceivablesMember us-gaap:FinancingReceivables1To29DaysPastDueMember 2022-12-31 0001695519 atgff:OtherAccountsReceivablesMember us-gaap:FinancingReceivables30To59DaysPastDueMember 2022-12-31 0001695519 atgff:OtherAccountsReceivablesMember us-gaap:FinancingReceivables60To89DaysPastDueMember 2022-12-31 0001695519 atgff:OtherAccountsReceivablesMember us-gaap:FinancingReceivablesEqualToGreaterThan90DaysPastDueMember 2022-12-31 0001695519 atgff:AllowanceFromDoubtfulAccountsMember 2022-12-31 0001695519 atgff:AllowanceFromDoubtfulAccountsMember us-gaap:FinancingReceivables1To29DaysPastDueMember 2022-12-31 0001695519 atgff:AllowanceFromDoubtfulAccountsMember us-gaap:FinancingReceivables30To59DaysPastDueMember 2022-12-31 0001695519 us-gaap:FinancingReceivables60To89DaysPastDueMember atgff:AllowanceFromDoubtfulAccountsMember 2022-12-31 0001695519 us-gaap:FinancingReceivablesEqualToGreaterThan90DaysPastDueMember atgff:AllowanceFromDoubtfulAccountsMember 2022-12-31 0001695519 us-gaap:FinancingReceivables1To29DaysPastDueMember 2022-12-31 0001695519 us-gaap:FinancingReceivables30To59DaysPastDueMember 2022-12-31 0001695519 us-gaap:FinancingReceivables60To89DaysPastDueMember 2022-12-31 0001695519 us-gaap:FinancingReceivablesEqualToGreaterThan90DaysPastDueMember 2022-12-31 0001695519 us-gaap:TradeAccountsReceivableMember 2021-12-31 0001695519 us-gaap:TradeAccountsReceivableMember us-gaap:FinancingReceivables1To29DaysPastDueMember 2021-12-31 0001695519 us-gaap:TradeAccountsReceivableMember us-gaap:FinancingReceivables30To59DaysPastDueMember 2021-12-31 0001695519 us-gaap:FinancingReceivables60To89DaysPastDueMember us-gaap:TradeAccountsReceivableMember 2021-12-31 0001695519 us-gaap:FinancingReceivablesEqualToGreaterThan90DaysPastDueMember us-gaap:TradeAccountsReceivableMember 2021-12-31 0001695519 atgff:OtherAccountsReceivablesMember 2021-12-31 0001695519 atgff:OtherAccountsReceivablesMember us-gaap:FinancingReceivables1To29DaysPastDueMember 2021-12-31 0001695519 atgff:OtherAccountsReceivablesMember us-gaap:FinancingReceivables30To59DaysPastDueMember 2021-12-31 0001695519 atgff:OtherAccountsReceivablesMember us-gaap:FinancingReceivables60To89DaysPastDueMember 2021-12-31 0001695519 atgff:OtherAccountsReceivablesMember us-gaap:FinancingReceivablesEqualToGreaterThan90DaysPastDueMember 2021-12-31 0001695519 atgff:AllowanceFromDoubtfulAccountsMember 2021-12-31 0001695519 atgff:AllowanceFromDoubtfulAccountsMember us-gaap:FinancingReceivables1To29DaysPastDueMember 2021-12-31 0001695519 atgff:AllowanceFromDoubtfulAccountsMember us-gaap:FinancingReceivables30To59DaysPastDueMember 2021-12-31 0001695519 us-gaap:FinancingReceivables60To89DaysPastDueMember atgff:AllowanceFromDoubtfulAccountsMember 2021-12-31 0001695519 us-gaap:FinancingReceivablesEqualToGreaterThan90DaysPastDueMember atgff:AllowanceFromDoubtfulAccountsMember 2021-12-31 0001695519 us-gaap:FinancingReceivables1To29DaysPastDueMember 2021-12-31 0001695519 us-gaap:FinancingReceivables30To59DaysPastDueMember 2021-12-31 0001695519 us-gaap:FinancingReceivables60To89DaysPastDueMember 2021-12-31 0001695519 us-gaap:FinancingReceivablesEqualToGreaterThan90DaysPastDueMember 2021-12-31 0001695519 us-gaap:AccountsReceivableMember atgff:UtilitiesSegmentMember 2021-12-31 0001695519 atgff:UtilitiesSegmentMember atgff:ContractAssetsMember 2021-12-31 0001695519 us-gaap:AccountsReceivableMember atgff:UtilitiesSegmentMember 2022-01-01 2022-12-31 0001695519 atgff:UtilitiesSegmentMember atgff:ContractAssetsMember 2022-01-01 2022-12-31 0001695519 us-gaap:AccountsReceivableMember atgff:UtilitiesSegmentMember 2022-12-31 0001695519 atgff:UtilitiesSegmentMember atgff:ContractAssetsMember 2022-12-31 0001695519 us-gaap:AccountsReceivableMember atgff:MidstreamSegmentMember 2021-12-31 0001695519 atgff:MidstreamSegmentMember atgff:ContractAssetsMember 2021-12-31 0001695519 us-gaap:AccountsReceivableMember atgff:MidstreamSegmentMember 2022-01-01 2022-12-31 0001695519 atgff:MidstreamSegmentMember atgff:ContractAssetsMember 2022-01-01 2022-12-31 0001695519 us-gaap:AccountsReceivableMember atgff:MidstreamSegmentMember 2022-12-31 0001695519 atgff:MidstreamSegmentMember atgff:ContractAssetsMember 2022-12-31 0001695519 us-gaap:AccountsReceivableMember 2022-12-31 0001695519 atgff:ContractAssetsMember 2022-12-31 0001695519 us-gaap:AccountsReceivableMember atgff:UtilitiesSegmentMember 2020-12-31 0001695519 atgff:UtilitiesSegmentMember atgff:ContractAssetsMember 2020-12-31 0001695519 atgff:UtilitiesSegmentMember atgff:OtherLongTermInvestmentsAndOtherAssetsMember 2020-12-31 0001695519 atgff:UtilitiesSegmentMember 2020-12-31 0001695519 us-gaap:AccountsReceivableMember atgff:UtilitiesSegmentMember 2021-01-01 2021-12-31 0001695519 atgff:UtilitiesSegmentMember atgff:ContractAssetsMember 2021-01-01 2021-12-31 0001695519 atgff:UtilitiesSegmentMember atgff:OtherLongTermInvestmentsAndOtherAssetsMember 2021-01-01 2021-12-31 0001695519 atgff:UtilitiesSegmentMember 2021-01-01 2021-12-31 0001695519 atgff:UtilitiesSegmentMember atgff:OtherLongTermInvestmentsAndOtherAssetsMember 2021-12-31 0001695519 us-gaap:AccountsReceivableMember atgff:MidstreamSegmentMember 2020-12-31 0001695519 atgff:MidstreamSegmentMember atgff:ContractAssetsMember 2020-12-31 0001695519 atgff:OtherLongTermInvestmentsAndOtherAssetsMember atgff:MidstreamSegmentMember 2020-12-31 0001695519 atgff:MidstreamSegmentMember 2020-12-31 0001695519 us-gaap:AccountsReceivableMember atgff:MidstreamSegmentMember 2021-01-01 2021-12-31 0001695519 atgff:MidstreamSegmentMember atgff:ContractAssetsMember 2021-01-01 2021-12-31 0001695519 atgff:OtherLongTermInvestmentsAndOtherAssetsMember atgff:MidstreamSegmentMember 2021-01-01 2021-12-31 0001695519 atgff:OtherLongTermInvestmentsAndOtherAssetsMember atgff:MidstreamSegmentMember 2021-12-31 0001695519 us-gaap:AccountsReceivableMember 2021-12-31 0001695519 atgff:ContractAssetsMember 2021-12-31 0001695519 atgff:OtherLongTermInvestmentsAndOtherAssetsMember 2021-12-31 0001695519 us-gaap:AccountsPayableAndAccruedLiabilitiesMember 2022-12-31 0001695519 us-gaap:ShortTermDebtMember 2022-12-31 0001695519 atgff:RiskManagementContractLiabilitiesMember 2022-12-31 0001695519 atgff:CurrentPortionOfLongTermDebtMember 2022-12-31 0001695519 us-gaap:LongTermDebtMember 2022-12-31 0001695519 atgff:DebtClassifiedAsHeldForSaleMember 2022-12-31 0001695519 atgff:SubordinatedHybridNotesMember 2022-12-31 0001695519 us-gaap:AccountsPayableAndAccruedLiabilitiesMember 2021-12-31 0001695519 us-gaap:ShortTermDebtMember 2021-12-31 0001695519 us-gaap:OtherCurrentLiabilitiesMember 2021-12-31 0001695519 atgff:RiskManagementContractLiabilitiesMember 2021-12-31 0001695519 atgff:CurrentPortionOfLongTermDebtMember 2021-12-31 0001695519 us-gaap:LongTermDebtMember 2021-12-31 0001695519 atgff:CommoditySalesContractsMember atgff:UtilitiesSegmentMember us-gaap:OperatingSegmentsMember 2022-01-01 2022-12-31 0001695519 atgff:CommoditySalesContractsMember us-gaap:OperatingSegmentsMember atgff:MidstreamSegmentMember 2022-01-01 2022-12-31 0001695519 atgff:CorporateAndOtherSegmentMember atgff:CommoditySalesContractsMember us-gaap:OperatingSegmentsMember 2022-01-01 2022-12-31 0001695519 atgff:CommoditySalesContractsMember 2022-01-01 2022-12-31 0001695519 atgff:MidstreamServiceContractsMember atgff:UtilitiesSegmentMember us-gaap:OperatingSegmentsMember 2022-01-01 2022-12-31 0001695519 atgff:MidstreamServiceContractsMember us-gaap:OperatingSegmentsMember atgff:MidstreamSegmentMember 2022-01-01 2022-12-31 0001695519 atgff:CorporateAndOtherSegmentMember atgff:MidstreamServiceContractsMember us-gaap:OperatingSegmentsMember 2022-01-01 2022-12-31 0001695519 atgff:MidstreamServiceContractsMember 2022-01-01 2022-12-31 0001695519 atgff:GasSalesAndTransportationServicesMember atgff:UtilitiesSegmentMember us-gaap:OperatingSegmentsMember 2022-01-01 2022-12-31 0001695519 atgff:GasSalesAndTransportationServicesMember us-gaap:OperatingSegmentsMember atgff:MidstreamSegmentMember 2022-01-01 2022-12-31 0001695519 atgff:CorporateAndOtherSegmentMember atgff:GasSalesAndTransportationServicesMember us-gaap:OperatingSegmentsMember 2022-01-01 2022-12-31 0001695519 atgff:GasSalesAndTransportationServicesMember 2022-01-01 2022-12-31 0001695519 atgff:UtilitiesSegmentMember atgff:StorageServicesMember us-gaap:OperatingSegmentsMember 2022-01-01 2022-12-31 0001695519 atgff:StorageServicesMember us-gaap:OperatingSegmentsMember atgff:MidstreamSegmentMember 2022-01-01 2022-12-31 0001695519 atgff:CorporateAndOtherSegmentMember atgff:StorageServicesMember us-gaap:OperatingSegmentsMember 2022-01-01 2022-12-31 0001695519 atgff:StorageServicesMember 2022-01-01 2022-12-31 0001695519 atgff:OtherProductAndServicesMember atgff:UtilitiesSegmentMember us-gaap:OperatingSegmentsMember 2022-01-01 2022-12-31 0001695519 atgff:OtherProductAndServicesMember us-gaap:OperatingSegmentsMember atgff:MidstreamSegmentMember 2022-01-01 2022-12-31 0001695519 atgff:CorporateAndOtherSegmentMember atgff:OtherProductAndServicesMember us-gaap:OperatingSegmentsMember 2022-01-01 2022-12-31 0001695519 atgff:OtherProductAndServicesMember 2022-01-01 2022-12-31 0001695519 atgff:UtilitiesSegmentMember us-gaap:OperatingSegmentsMember 2022-01-01 2022-12-31 0001695519 us-gaap:OperatingSegmentsMember atgff:MidstreamSegmentMember 2022-01-01 2022-12-31 0001695519 atgff:CorporateAndOtherSegmentMember us-gaap:OperatingSegmentsMember 2022-01-01 2022-12-31 0001695519 atgff:RevenueFromAlternativeRevenueProgramsMember atgff:UtilitiesSegmentMember us-gaap:OperatingSegmentsMember 2022-01-01 2022-12-31 0001695519 atgff:RevenueFromAlternativeRevenueProgramsMember us-gaap:OperatingSegmentsMember atgff:MidstreamSegmentMember 2022-01-01 2022-12-31 0001695519 atgff:CorporateAndOtherSegmentMember atgff:RevenueFromAlternativeRevenueProgramsMember us-gaap:OperatingSegmentsMember 2022-01-01 2022-12-31 0001695519 atgff:RevenueFromAlternativeRevenueProgramsMember 2022-01-01 2022-12-31 0001695519 atgff:LeasingRevenueMember atgff:UtilitiesSegmentMember us-gaap:OperatingSegmentsMember 2022-01-01 2022-12-31 0001695519 atgff:LeasingRevenueMember us-gaap:OperatingSegmentsMember atgff:MidstreamSegmentMember 2022-01-01 2022-12-31 0001695519 atgff:CorporateAndOtherSegmentMember atgff:LeasingRevenueMember us-gaap:OperatingSegmentsMember 2022-01-01 2022-12-31 0001695519 atgff:LeasingRevenueMember 2022-01-01 2022-12-31 0001695519 atgff:RiskManagementAndTradingActivitiesMember atgff:UtilitiesSegmentMember us-gaap:OperatingSegmentsMember 2022-01-01 2022-12-31 0001695519 atgff:RiskManagementAndTradingActivitiesMember us-gaap:OperatingSegmentsMember atgff:MidstreamSegmentMember 2022-01-01 2022-12-31 0001695519 atgff:CorporateAndOtherSegmentMember atgff:RiskManagementAndTradingActivitiesMember us-gaap:OperatingSegmentsMember 2022-01-01 2022-12-31 0001695519 atgff:RiskManagementAndTradingActivitiesMember 2022-01-01 2022-12-31 0001695519 atgff:OtherSourcesOfRevenueMember atgff:UtilitiesSegmentMember us-gaap:OperatingSegmentsMember 2022-01-01 2022-12-31 0001695519 atgff:OtherSourcesOfRevenueMember us-gaap:OperatingSegmentsMember atgff:MidstreamSegmentMember 2022-01-01 2022-12-31 0001695519 atgff:OtherSourcesOfRevenueMember atgff:CorporateAndOtherSegmentMember us-gaap:OperatingSegmentsMember 2022-01-01 2022-12-31 0001695519 atgff:OtherSourcesOfRevenueMember 2022-01-01 2022-12-31 0001695519 atgff:CommoditySalesContractsMember atgff:UtilitiesSegmentMember us-gaap:OperatingSegmentsMember 2021-01-01 2021-12-31 0001695519 atgff:CommoditySalesContractsMember us-gaap:OperatingSegmentsMember atgff:MidstreamSegmentMember 2021-01-01 2021-12-31 0001695519 atgff:CorporateAndOtherSegmentMember atgff:CommoditySalesContractsMember us-gaap:OperatingSegmentsMember 2021-01-01 2021-12-31 0001695519 atgff:CommoditySalesContractsMember 2021-01-01 2021-12-31 0001695519 atgff:MidstreamServiceContractsMember atgff:UtilitiesSegmentMember us-gaap:OperatingSegmentsMember 2021-01-01 2021-12-31 0001695519 atgff:MidstreamServiceContractsMember us-gaap:OperatingSegmentsMember atgff:MidstreamSegmentMember 2021-01-01 2021-12-31 0001695519 atgff:CorporateAndOtherSegmentMember atgff:MidstreamServiceContractsMember us-gaap:OperatingSegmentsMember 2021-01-01 2021-12-31 0001695519 atgff:MidstreamServiceContractsMember 2021-01-01 2021-12-31 0001695519 atgff:GasSalesAndTransportationServicesMember atgff:UtilitiesSegmentMember us-gaap:OperatingSegmentsMember 2021-01-01 2021-12-31 0001695519 atgff:GasSalesAndTransportationServicesMember us-gaap:OperatingSegmentsMember atgff:MidstreamSegmentMember 2021-01-01 2021-12-31 0001695519 atgff:CorporateAndOtherSegmentMember atgff:GasSalesAndTransportationServicesMember us-gaap:OperatingSegmentsMember 2021-01-01 2021-12-31 0001695519 atgff:GasSalesAndTransportationServicesMember 2021-01-01 2021-12-31 0001695519 atgff:UtilitiesSegmentMember atgff:StorageServicesMember us-gaap:OperatingSegmentsMember 2021-01-01 2021-12-31 0001695519 atgff:StorageServicesMember us-gaap:OperatingSegmentsMember atgff:MidstreamSegmentMember 2021-01-01 2021-12-31 0001695519 atgff:CorporateAndOtherSegmentMember atgff:StorageServicesMember us-gaap:OperatingSegmentsMember 2021-01-01 2021-12-31 0001695519 atgff:StorageServicesMember 2021-01-01 2021-12-31 0001695519 atgff:OtherProductAndServicesMember atgff:UtilitiesSegmentMember us-gaap:OperatingSegmentsMember 2021-01-01 2021-12-31 0001695519 atgff:OtherProductAndServicesMember us-gaap:OperatingSegmentsMember atgff:MidstreamSegmentMember 2021-01-01 2021-12-31 0001695519 atgff:CorporateAndOtherSegmentMember atgff:OtherProductAndServicesMember us-gaap:OperatingSegmentsMember 2021-01-01 2021-12-31 0001695519 atgff:OtherProductAndServicesMember 2021-01-01 2021-12-31 0001695519 atgff:UtilitiesSegmentMember us-gaap:OperatingSegmentsMember 2021-01-01 2021-12-31 0001695519 us-gaap:OperatingSegmentsMember atgff:MidstreamSegmentMember 2021-01-01 2021-12-31 0001695519 atgff:CorporateAndOtherSegmentMember us-gaap:OperatingSegmentsMember 2021-01-01 2021-12-31 0001695519 atgff:RevenueFromAlternativeRevenueProgramsMember atgff:UtilitiesSegmentMember us-gaap:OperatingSegmentsMember 2021-01-01 2021-12-31 0001695519 atgff:RevenueFromAlternativeRevenueProgramsMember us-gaap:OperatingSegmentsMember atgff:MidstreamSegmentMember 2021-01-01 2021-12-31 0001695519 atgff:CorporateAndOtherSegmentMember atgff:RevenueFromAlternativeRevenueProgramsMember us-gaap:OperatingSegmentsMember 2021-01-01 2021-12-31 0001695519 atgff:RevenueFromAlternativeRevenueProgramsMember 2021-01-01 2021-12-31 0001695519 atgff:LeasingRevenueMember atgff:UtilitiesSegmentMember us-gaap:OperatingSegmentsMember 2021-01-01 2021-12-31 0001695519 atgff:LeasingRevenueMember us-gaap:OperatingSegmentsMember atgff:MidstreamSegmentMember 2021-01-01 2021-12-31 0001695519 atgff:CorporateAndOtherSegmentMember atgff:LeasingRevenueMember us-gaap:OperatingSegmentsMember 2021-01-01 2021-12-31 0001695519 atgff:LeasingRevenueMember 2021-01-01 2021-12-31 0001695519 atgff:RiskManagementAndTradingActivitiesMember atgff:UtilitiesSegmentMember us-gaap:OperatingSegmentsMember 2021-01-01 2021-12-31 0001695519 atgff:RiskManagementAndTradingActivitiesMember us-gaap:OperatingSegmentsMember atgff:MidstreamSegmentMember 2021-01-01 2021-12-31 0001695519 atgff:CorporateAndOtherSegmentMember atgff:RiskManagementAndTradingActivitiesMember us-gaap:OperatingSegmentsMember 2021-01-01 2021-12-31 0001695519 atgff:RiskManagementAndTradingActivitiesMember 2021-01-01 2021-12-31 0001695519 atgff:OtherSourcesOfRevenueMember atgff:UtilitiesSegmentMember us-gaap:OperatingSegmentsMember 2021-01-01 2021-12-31 0001695519 atgff:OtherSourcesOfRevenueMember us-gaap:OperatingSegmentsMember atgff:MidstreamSegmentMember 2021-01-01 2021-12-31 0001695519 atgff:OtherSourcesOfRevenueMember atgff:CorporateAndOtherSegmentMember us-gaap:OperatingSegmentsMember 2021-01-01 2021-12-31 0001695519 atgff:OtherSourcesOfRevenueMember 2021-01-01 2021-12-31 0001695519 atgff:RiskManagementAndTradingActivitiesMember atgff:GailMember 2021-01-01 2021-12-31 0001695519 atgff:GailMember 2018-03-31 2022-12-31 0001695519 atgff:GasSalesAndTransportationServicesMember atgff:UtilitiesSegmentMember 2022-12-31 atgff:component 0001695519 atgff:UtilitiesSegmentMember atgff:GasStorageServicesMember 2022-12-31 0001695519 atgff:UtilitiesSegmentMember atgff:GasStorageServicesMember us-gaap:OperatingSegmentsMember 2022-01-01 2022-12-31 0001695519 atgff:CommoditySalesContractsMember atgff:UtilitiesSegmentMember srt:MinimumMember us-gaap:OperatingSegmentsMember 2022-01-01 2022-12-31 0001695519 atgff:CommoditySalesContractsMember srt:MaximumMember atgff:UtilitiesSegmentMember us-gaap:OperatingSegmentsMember 2022-01-01 2022-12-31 0001695519 atgff:MidstreamServiceContractsMember 2023-01-01 2022-12-31 0001695519 atgff:MidstreamServiceContractsMember 2024-01-01 2022-12-31 0001695519 atgff:MidstreamServiceContractsMember 2025-01-01 2022-12-31 0001695519 2026-01-01 atgff:MidstreamServiceContractsMember 2022-12-31 0001695519 2027-01-01 atgff:MidstreamServiceContractsMember 2022-12-31 0001695519 atgff:MidstreamServiceContractsMember 2028-01-01 2022-12-31 0001695519 atgff:MidstreamServiceContractsMember 2022-12-31 0001695519 2023-01-01 atgff:StorageServicesMember 2022-12-31 0001695519 2024-01-01 atgff:StorageServicesMember 2022-12-31 0001695519 atgff:StorageServicesMember 2025-01-01 2022-12-31 0001695519 2026-01-01 atgff:StorageServicesMember 2022-12-31 0001695519 2027-01-01 atgff:StorageServicesMember 2022-12-31 0001695519 2028-01-01 atgff:StorageServicesMember 2022-12-31 0001695519 atgff:StorageServicesMember 2022-12-31 0001695519 atgff:OtherProductAndServicesMember 2023-01-01 2022-12-31 0001695519 atgff:OtherProductAndServicesMember 2024-01-01 2022-12-31 0001695519 atgff:OtherProductAndServicesMember 2025-01-01 2022-12-31 0001695519 2026-01-01 atgff:OtherProductAndServicesMember 2022-12-31 0001695519 2027-01-01 atgff:OtherProductAndServicesMember 2022-12-31 0001695519 atgff:OtherProductAndServicesMember 2028-01-01 2022-12-31 0001695519 atgff:OtherProductAndServicesMember 2022-12-31 0001695519 2023-01-01 2022-12-31 0001695519 2024-01-01 2022-12-31 0001695519 2025-01-01 2022-12-31 0001695519 2026-01-01 2022-12-31 0001695519 2027-01-01 2022-12-31 0001695519 2028-01-01 2022-12-31 iso4217:USD xbrli:shares 0001695519 us-gaap:SeriesAPreferredStockMember us-gaap:PreferredStockMember 2022-12-31 0001695519 us-gaap:SeriesAPreferredStockMember us-gaap:PreferredStockMember 2021-12-31 0001695519 us-gaap:SeriesBPreferredStockMember us-gaap:PreferredStockMember 2022-12-31 0001695519 us-gaap:SeriesBPreferredStockMember us-gaap:PreferredStockMember 2021-12-31 0001695519 us-gaap:PreferredStockMember us-gaap:SeriesCPreferredStockMember 2022-12-31 0001695519 us-gaap:PreferredStockMember us-gaap:SeriesCPreferredStockMember 2021-12-31 0001695519 us-gaap:PreferredStockMember us-gaap:SeriesEPreferredStockMember 2022-12-31 0001695519 us-gaap:PreferredStockMember us-gaap:SeriesEPreferredStockMember 2021-12-31 0001695519 us-gaap:PreferredStockMember us-gaap:SeriesGPreferredStockMember 2022-12-31 0001695519 us-gaap:PreferredStockMember us-gaap:SeriesGPreferredStockMember 2021-12-31 0001695519 us-gaap:PreferredStockMember us-gaap:SeriesHPreferredStockMember 2022-12-31 0001695519 us-gaap:PreferredStockMember us-gaap:SeriesHPreferredStockMember 2021-12-31 0001695519 us-gaap:PreferredStockMember atgff:SeriesKPreferredStockMember 2022-12-31 0001695519 us-gaap:PreferredStockMember atgff:SeriesKPreferredStockMember 2021-12-31 0001695519 us-gaap:SeriesCPreferredStockMember 2022-09-30 2022-09-30 0001695519 atgff:SeriesKPreferredStockMember 2022-03-31 2022-03-31 0001695519 us-gaap:SeriesAPreferredStockMember 2022-01-01 2022-12-31 0001695519 us-gaap:SeriesAPreferredStockMember 2022-12-31 0001695519 us-gaap:SeriesBPreferredStockMember 2022-12-31 0001695519 us-gaap:SeriesEPreferredStockMember 2022-01-01 2022-12-31 0001695519 us-gaap:SeriesEPreferredStockMember 2022-12-31 0001695519 us-gaap:SeriesGPreferredStockMember 2022-01-01 2022-12-31 0001695519 us-gaap:SeriesGPreferredStockMember 2022-12-31 0001695519 us-gaap:SeriesHPreferredStockMember 2022-12-31 0001695519 us-gaap:SeriesFPreferredStockMember 2022-12-31 0001695519 us-gaap:SeriesAPreferredStockMember atgff:FiveYearGovernmentOfCanadaBondYieldMember 2022-12-31 0001695519 atgff:FiveYearGovernmentOfCanadaBondYieldMember us-gaap:SeriesEPreferredStockMember 2022-12-31 0001695519 atgff:FiveYearGovernmentOfCanadaBondYieldMember us-gaap:SeriesGPreferredStockMember 2022-12-31 0001695519 us-gaap:SeriesBPreferredStockMember atgff:A90DayGovernmentOfCanadaTreasuryBillRateMember 2022-12-31 0001695519 us-gaap:SeriesHPreferredStockMember atgff:A90DayGovernmentOfCanadaTreasuryBillRateMember 2022-12-31 0001695519 atgff:ShareOptionPlanMember 2022-12-31 0001695519 srt:MinimumMember atgff:ShareOptionPlanMember 2022-01-01 2022-12-31 0001695519 srt:MaximumMember atgff:ShareOptionPlanMember 2022-01-01 2022-12-31 0001695519 atgff:ShareOptionPlanMember 2021-12-31 0001695519 srt:MaximumMember atgff:ShareOptionPlanMember 2021-01-01 2021-12-31 0001695519 atgff:ExercisePriceRangeOneMember 2022-01-01 2022-12-31 0001695519 atgff:ExercisePriceRangeOneMember 2022-12-31 0001695519 atgff:ExercisePriceRangeTwoMember 2022-01-01 2022-12-31 0001695519 atgff:ExercisePriceRangeTwoMember 2022-12-31 0001695519 atgff:ExercisePriceRangeThreeMember 2022-01-01 2022-12-31 0001695519 atgff:ExercisePriceRangeThreeMember 2022-12-31 0001695519 atgff:MidTermIncentivePlanMember srt:MinimumMember 2022-01-01 2022-12-31 0001695519 atgff:MidTermIncentiveAndDeferredShareUnitPlansMember 2022-01-01 2022-12-31 0001695519 atgff:MidTermIncentiveAndDeferredShareUnitPlansMember 2021-01-01 2021-12-31 0001695519 atgff:MidTermIncentiveAndDeferredShareUnitPlansMember 2022-12-31 0001695519 atgff:MidTermIncentiveAndDeferredShareUnitPlansMember 2021-12-31 0001695519 country:CA atgff:DefinedBenefitPlanMember 2022-12-31 atgff:plan 0001695519 atgff:DefinedBenefitPlanMember 2022-12-31 atgff:division 0001695519 us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember 2022-12-31 0001695519 us-gaap:UnderfundedPlanMember country:CA atgff:DefinedBenefitPlanMember 2022-12-31 0001695519 country:CA atgff:DefinedBenefitPlanMember 2022-01-01 2022-12-31 0001695519 atgff:PostRetirementBenefitsMember country:CA 2022-12-31 0001695519 us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember 2022-12-31 atgff:age 0001695519 us-gaap:UnderfundedPlanMember us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember 2022-12-31 0001695519 us-gaap:ForeignPlanMember us-gaap:FundedPlanMember atgff:PostRetirementBenefitsMember 2022-12-31 0001695519 atgff:DefinedBenefitPlanNotFundedMember us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember 2022-12-31 0001695519 country:CA atgff:DefinedBenefitPlanMember 2021-12-31 0001695519 atgff:PostRetirementBenefitsMember country:CA 2021-12-31 0001695519 us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember 2021-12-31 0001695519 us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember 2021-12-31 0001695519 atgff:DefinedBenefitPlanMember 2021-12-31 0001695519 atgff:PostRetirementBenefitsMember 2021-12-31 0001695519 atgff:PostRetirementBenefitsMember country:CA 2022-01-01 2022-12-31 0001695519 us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember 2022-01-01 2022-12-31 0001695519 us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember 2022-01-01 2022-12-31 0001695519 atgff:DefinedBenefitPlanMember 2022-01-01 2022-12-31 0001695519 atgff:PostRetirementBenefitsMember 2022-01-01 2022-12-31 0001695519 atgff:PostRetirementBenefitsMember 2022-12-31 0001695519 country:CA atgff:DefinedBenefitPlanMember 2020-12-31 0001695519 atgff:PostRetirementBenefitsMember country:CA 2020-12-31 0001695519 us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember 2020-12-31 0001695519 us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember 2020-12-31 0001695519 atgff:DefinedBenefitPlanMember 2020-12-31 0001695519 atgff:PostRetirementBenefitsMember 2020-12-31 0001695519 country:CA atgff:DefinedBenefitPlanMember 2021-01-01 2021-12-31 0001695519 atgff:PostRetirementBenefitsMember country:CA 2021-01-01 2021-12-31 0001695519 us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember 2021-01-01 2021-12-31 0001695519 us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember 2021-01-01 2021-12-31 0001695519 atgff:DefinedBenefitPlanMember 2021-01-01 2021-12-31 0001695519 atgff:PostRetirementBenefitsMember 2021-01-01 2021-12-31 0001695519 country:CA 2022-12-31 0001695519 us-gaap:ForeignPlanMember 2022-12-31 0001695519 country:CA 2021-12-31 0001695519 us-gaap:ForeignPlanMember 2021-12-31 0001695519 country:CA us-gaap:FixedIncomeSecuritiesMember 2022-12-31 0001695519 us-gaap:FixedIncomeSecuritiesMember atgff:SemcoMember 2022-12-31 0001695519 atgff:WglHoldingsMember us-gaap:FixedIncomeSecuritiesMember srt:MinimumMember 2022-12-31 0001695519 atgff:WglHoldingsMember srt:MaximumMember us-gaap:FixedIncomeSecuritiesMember 2022-12-31 0001695519 country:CA us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember atgff:DefinedBenefitPlanMember us-gaap:CashAndCashEquivalentsMember 2022-12-31 0001695519 us-gaap:FairValueInputsLevel1Member country:CA atgff:DefinedBenefitPlanMember us-gaap:CashAndCashEquivalentsMember 2022-12-31 0001695519 country:CA atgff:DefinedBenefitPlanMember us-gaap:FairValueInputsLevel2Member us-gaap:CashAndCashEquivalentsMember 2022-12-31 0001695519 atgff:CanadianBondsMember country:CA us-gaap:FixedIncomeSecuritiesMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember atgff:DefinedBenefitPlanMember 2022-12-31 0001695519 atgff:CanadianBondsMember us-gaap:FairValueInputsLevel1Member country:CA us-gaap:FixedIncomeSecuritiesMember atgff:DefinedBenefitPlanMember 2022-12-31 0001695519 atgff:CanadianBondsMember country:CA us-gaap:FixedIncomeSecuritiesMember atgff:DefinedBenefitPlanMember us-gaap:FairValueInputsLevel2Member 2022-12-31 0001695519 country:CA us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember atgff:DefinedBenefitPlanMember 2022-12-31 0001695519 us-gaap:FairValueInputsLevel1Member country:CA atgff:DefinedBenefitPlanMember 2022-12-31 0001695519 country:CA atgff:DefinedBenefitPlanMember us-gaap:FairValueInputsLevel2Member 2022-12-31 0001695519 country:CA us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember atgff:DefinedBenefitPlanMember us-gaap:CashAndCashEquivalentsMember 2021-12-31 0001695519 us-gaap:FairValueInputsLevel1Member country:CA atgff:DefinedBenefitPlanMember us-gaap:CashAndCashEquivalentsMember 2021-12-31 0001695519 country:CA atgff:DefinedBenefitPlanMember us-gaap:FairValueInputsLevel2Member us-gaap:CashAndCashEquivalentsMember 2021-12-31 0001695519 atgff:CanadianBondsMember country:CA us-gaap:FixedIncomeSecuritiesMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember atgff:DefinedBenefitPlanMember 2021-12-31 0001695519 atgff:CanadianBondsMember us-gaap:FairValueInputsLevel1Member country:CA us-gaap:FixedIncomeSecuritiesMember atgff:DefinedBenefitPlanMember 2021-12-31 0001695519 atgff:CanadianBondsMember country:CA us-gaap:FixedIncomeSecuritiesMember atgff:DefinedBenefitPlanMember us-gaap:FairValueInputsLevel2Member 2021-12-31 0001695519 country:CA us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember atgff:DefinedBenefitPlanMember 2021-12-31 0001695519 us-gaap:FairValueInputsLevel1Member country:CA atgff:DefinedBenefitPlanMember 2021-12-31 0001695519 country:CA atgff:DefinedBenefitPlanMember us-gaap:FairValueInputsLevel2Member 2021-12-31 0001695519 us-gaap:ForeignPlanMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember atgff:DefinedBenefitPlanMember us-gaap:CashAndCashEquivalentsMember 2022-12-31 0001695519 us-gaap:FairValueInputsLevel1Member us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember us-gaap:CashAndCashEquivalentsMember 2022-12-31 0001695519 us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember us-gaap:FairValueInputsLevel2Member us-gaap:CashAndCashEquivalentsMember 2022-12-31 0001695519 us-gaap:EquitySecuritiesMember us-gaap:ForeignPlanMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember atgff:DefinedBenefitPlanMember us-gaap:GeographicDistributionDomesticMember 2022-12-31 0001695519 us-gaap:EquitySecuritiesMember us-gaap:FairValueInputsLevel1Member us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember us-gaap:GeographicDistributionDomesticMember 2022-12-31 0001695519 us-gaap:EquitySecuritiesMember us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember us-gaap:FairValueInputsLevel2Member us-gaap:GeographicDistributionDomesticMember 2022-12-31 0001695519 us-gaap:GeographicDistributionForeignMember us-gaap:EquitySecuritiesMember us-gaap:ForeignPlanMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember atgff:DefinedBenefitPlanMember 2022-12-31 0001695519 us-gaap:GeographicDistributionForeignMember us-gaap:EquitySecuritiesMember us-gaap:FairValueInputsLevel1Member us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember 2022-12-31 0001695519 us-gaap:GeographicDistributionForeignMember us-gaap:EquitySecuritiesMember us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember us-gaap:FairValueInputsLevel2Member 2022-12-31 0001695519 us-gaap:ForeignPlanMember us-gaap:FixedIncomeSecuritiesMember us-gaap:USTreasuryAndGovernmentMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember atgff:DefinedBenefitPlanMember 2022-12-31 0001695519 us-gaap:FairValueInputsLevel1Member us-gaap:ForeignPlanMember us-gaap:FixedIncomeSecuritiesMember us-gaap:USTreasuryAndGovernmentMember atgff:DefinedBenefitPlanMember 2022-12-31 0001695519 us-gaap:ForeignPlanMember us-gaap:FixedIncomeSecuritiesMember us-gaap:USTreasuryAndGovernmentMember atgff:DefinedBenefitPlanMember us-gaap:FairValueInputsLevel2Member 2022-12-31 0001695519 us-gaap:ForeignPlanMember us-gaap:FixedIncomeSecuritiesMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember atgff:DefinedBenefitPlanMember us-gaap:CorporateDebtSecuritiesMember 2022-12-31 0001695519 us-gaap:FairValueInputsLevel1Member us-gaap:ForeignPlanMember us-gaap:FixedIncomeSecuritiesMember atgff:DefinedBenefitPlanMember us-gaap:CorporateDebtSecuritiesMember 2022-12-31 0001695519 us-gaap:ForeignPlanMember us-gaap:FixedIncomeSecuritiesMember atgff:DefinedBenefitPlanMember us-gaap:CorporateDebtSecuritiesMember us-gaap:FairValueInputsLevel2Member 2022-12-31 0001695519 us-gaap:ForeignPlanMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember atgff:DefinedBenefitPlanMember us-gaap:DefinedBenefitPlanDerivativeMember 2022-12-31 0001695519 us-gaap:FairValueInputsLevel1Member us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember us-gaap:DefinedBenefitPlanDerivativeMember 2022-12-31 0001695519 us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember us-gaap:FairValueInputsLevel2Member us-gaap:DefinedBenefitPlanDerivativeMember 2022-12-31 0001695519 us-gaap:ForeignPlanMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember atgff:DefinedBenefitPlanMember atgff:DefinedBenefitPlanOtherMember 2022-12-31 0001695519 us-gaap:FairValueInputsLevel1Member us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember atgff:DefinedBenefitPlanOtherMember 2022-12-31 0001695519 us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember us-gaap:FairValueInputsLevel2Member atgff:DefinedBenefitPlanOtherMember 2022-12-31 0001695519 us-gaap:ForeignPlanMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember atgff:DefinedBenefitPlanMember 2022-12-31 0001695519 us-gaap:FairValueInputsLevel1Member us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember 2022-12-31 0001695519 us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember us-gaap:FairValueInputsLevel2Member 2022-12-31 0001695519 us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember atgff:IncomeProducingPropertiesMember 2022-12-31 0001695519 us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember atgff:CollectiveTrustFundMember 2022-12-31 0001695519 us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember atgff:NetReceivableMember 2022-01-01 2022-12-31 0001695519 us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember atgff:NetReceivableMember 2022-12-31 0001695519 us-gaap:ForeignPlanMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember atgff:DefinedBenefitPlanMember us-gaap:CashAndCashEquivalentsMember 2021-12-31 0001695519 us-gaap:FairValueInputsLevel1Member us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember us-gaap:CashAndCashEquivalentsMember 2021-12-31 0001695519 us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember us-gaap:FairValueInputsLevel2Member us-gaap:CashAndCashEquivalentsMember 2021-12-31 0001695519 us-gaap:EquitySecuritiesMember us-gaap:ForeignPlanMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember atgff:DefinedBenefitPlanMember us-gaap:GeographicDistributionDomesticMember 2021-12-31 0001695519 us-gaap:EquitySecuritiesMember us-gaap:FairValueInputsLevel1Member us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember us-gaap:GeographicDistributionDomesticMember 2021-12-31 0001695519 us-gaap:EquitySecuritiesMember us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember us-gaap:FairValueInputsLevel2Member us-gaap:GeographicDistributionDomesticMember 2021-12-31 0001695519 us-gaap:GeographicDistributionForeignMember us-gaap:EquitySecuritiesMember us-gaap:ForeignPlanMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember atgff:DefinedBenefitPlanMember 2021-12-31 0001695519 us-gaap:GeographicDistributionForeignMember us-gaap:EquitySecuritiesMember us-gaap:FairValueInputsLevel1Member us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember 2021-12-31 0001695519 us-gaap:GeographicDistributionForeignMember us-gaap:EquitySecuritiesMember us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember us-gaap:FairValueInputsLevel2Member 2021-12-31 0001695519 us-gaap:ForeignPlanMember us-gaap:FixedIncomeSecuritiesMember us-gaap:USTreasuryAndGovernmentMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember atgff:DefinedBenefitPlanMember 2021-12-31 0001695519 us-gaap:FairValueInputsLevel1Member us-gaap:ForeignPlanMember us-gaap:FixedIncomeSecuritiesMember us-gaap:USTreasuryAndGovernmentMember atgff:DefinedBenefitPlanMember 2021-12-31 0001695519 us-gaap:ForeignPlanMember us-gaap:FixedIncomeSecuritiesMember us-gaap:USTreasuryAndGovernmentMember atgff:DefinedBenefitPlanMember us-gaap:FairValueInputsLevel2Member 2021-12-31 0001695519 us-gaap:ForeignPlanMember us-gaap:FixedIncomeSecuritiesMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember atgff:DefinedBenefitPlanMember us-gaap:CorporateDebtSecuritiesMember 2021-12-31 0001695519 us-gaap:FairValueInputsLevel1Member us-gaap:ForeignPlanMember us-gaap:FixedIncomeSecuritiesMember atgff:DefinedBenefitPlanMember us-gaap:CorporateDebtSecuritiesMember 2021-12-31 0001695519 us-gaap:ForeignPlanMember us-gaap:FixedIncomeSecuritiesMember atgff:DefinedBenefitPlanMember us-gaap:CorporateDebtSecuritiesMember us-gaap:FairValueInputsLevel2Member 2021-12-31 0001695519 us-gaap:ForeignPlanMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember atgff:DefinedBenefitPlanMember us-gaap:DefinedBenefitPlanDerivativeMember 2021-12-31 0001695519 us-gaap:FairValueInputsLevel1Member us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember us-gaap:DefinedBenefitPlanDerivativeMember 2021-12-31 0001695519 us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember us-gaap:FairValueInputsLevel2Member us-gaap:DefinedBenefitPlanDerivativeMember 2021-12-31 0001695519 us-gaap:ForeignPlanMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember atgff:DefinedBenefitPlanMember atgff:DefinedBenefitPlanOtherMember 2021-12-31 0001695519 us-gaap:FairValueInputsLevel1Member us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember atgff:DefinedBenefitPlanOtherMember 2021-12-31 0001695519 us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember us-gaap:FairValueInputsLevel2Member atgff:DefinedBenefitPlanOtherMember 2021-12-31 0001695519 us-gaap:ForeignPlanMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember atgff:DefinedBenefitPlanMember 2021-12-31 0001695519 us-gaap:FairValueInputsLevel1Member us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember 2021-12-31 0001695519 us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember us-gaap:FairValueInputsLevel2Member 2021-12-31 0001695519 us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember atgff:PrivateEquityLimitedPartnershipMember 2021-12-31 0001695519 us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember atgff:IncomeProducingPropertiesMember 2021-12-31 0001695519 us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember atgff:CollectiveTrustFundMember 2021-12-31 0001695519 us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember atgff:NetReceivableMember 2021-01-01 2021-12-31 0001695519 us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember atgff:NetReceivableMember 2021-12-31 0001695519 us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember atgff:IncomeProducingPropertiesMember atgff:IncomeProducingPropertyMember 2022-12-31 0001695519 us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember atgff:IncomeProducingPropertiesMember atgff:IncomeProducingPropertyMember 2021-12-31 0001695519 us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember atgff:IncomeProducingPropertyMember 2022-12-31 0001695519 us-gaap:ForeignPlanMember atgff:DefinedBenefitPlanMember atgff:IncomeProducingPropertyMember 2021-12-31 0001695519 us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:CashAndCashEquivalentsMember 2022-12-31 0001695519 us-gaap:FairValueInputsLevel1Member us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:CashAndCashEquivalentsMember 2022-12-31 0001695519 us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FairValueInputsLevel2Member us-gaap:CashAndCashEquivalentsMember 2022-12-31 0001695519 us-gaap:GeographicDistributionForeignMember us-gaap:EquitySecuritiesMember us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember 2022-12-31 0001695519 us-gaap:GeographicDistributionForeignMember us-gaap:EquitySecuritiesMember us-gaap:FairValueInputsLevel1Member us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember 2022-12-31 0001695519 us-gaap:GeographicDistributionForeignMember us-gaap:EquitySecuritiesMember us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FairValueInputsLevel2Member 2022-12-31 0001695519 us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FixedIncomeSecuritiesMember us-gaap:USTreasuryAndGovernmentMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember 2022-12-31 0001695519 us-gaap:FairValueInputsLevel1Member us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FixedIncomeSecuritiesMember us-gaap:USTreasuryAndGovernmentMember 2022-12-31 0001695519 us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FixedIncomeSecuritiesMember us-gaap:USTreasuryAndGovernmentMember us-gaap:FairValueInputsLevel2Member 2022-12-31 0001695519 us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FixedIncomeSecuritiesMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:CorporateDebtSecuritiesMember 2022-12-31 0001695519 us-gaap:FairValueInputsLevel1Member us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FixedIncomeSecuritiesMember us-gaap:CorporateDebtSecuritiesMember 2022-12-31 0001695519 us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FixedIncomeSecuritiesMember us-gaap:CorporateDebtSecuritiesMember us-gaap:FairValueInputsLevel2Member 2022-12-31 0001695519 us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember atgff:DefinedBenefitPlanOtherMember 2022-12-31 0001695519 us-gaap:FairValueInputsLevel1Member us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember atgff:DefinedBenefitPlanOtherMember 2022-12-31 0001695519 us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FairValueInputsLevel2Member atgff:DefinedBenefitPlanOtherMember 2022-12-31 0001695519 us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember 2022-12-31 0001695519 us-gaap:FairValueInputsLevel1Member us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember 2022-12-31 0001695519 us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FairValueInputsLevel2Member 2022-12-31 0001695519 us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember atgff:CommingledFundsMember 2022-12-31 0001695519 us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:CashAndCashEquivalentsMember 2021-12-31 0001695519 us-gaap:FairValueInputsLevel1Member us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:CashAndCashEquivalentsMember 2021-12-31 0001695519 us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FairValueInputsLevel2Member us-gaap:CashAndCashEquivalentsMember 2021-12-31 0001695519 us-gaap:GeographicDistributionForeignMember us-gaap:EquitySecuritiesMember us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember 2021-12-31 0001695519 us-gaap:GeographicDistributionForeignMember us-gaap:EquitySecuritiesMember us-gaap:FairValueInputsLevel1Member us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember 2021-12-31 0001695519 us-gaap:GeographicDistributionForeignMember us-gaap:EquitySecuritiesMember us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FairValueInputsLevel2Member 2021-12-31 0001695519 us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FixedIncomeSecuritiesMember us-gaap:USTreasuryAndGovernmentMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember 2021-12-31 0001695519 us-gaap:FairValueInputsLevel1Member us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FixedIncomeSecuritiesMember us-gaap:USTreasuryAndGovernmentMember 2021-12-31 0001695519 us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FixedIncomeSecuritiesMember us-gaap:USTreasuryAndGovernmentMember us-gaap:FairValueInputsLevel2Member 2021-12-31 0001695519 us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FixedIncomeSecuritiesMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:CorporateDebtSecuritiesMember 2021-12-31 0001695519 us-gaap:FairValueInputsLevel1Member us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FixedIncomeSecuritiesMember us-gaap:CorporateDebtSecuritiesMember 2021-12-31 0001695519 us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FixedIncomeSecuritiesMember us-gaap:CorporateDebtSecuritiesMember us-gaap:FairValueInputsLevel2Member 2021-12-31 0001695519 us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember atgff:DefinedBenefitPlanOtherMember 2021-12-31 0001695519 us-gaap:FairValueInputsLevel1Member us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember atgff:DefinedBenefitPlanOtherMember 2021-12-31 0001695519 us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FairValueInputsLevel2Member atgff:DefinedBenefitPlanOtherMember 2021-12-31 0001695519 us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember 2021-12-31 0001695519 us-gaap:FairValueInputsLevel1Member us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember 2021-12-31 0001695519 us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FairValueInputsLevel2Member 2021-12-31 0001695519 us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember atgff:CommingledFundsMember 2021-12-31 0001695519 atgff:WglHoldingsMember us-gaap:ForeignPlanMember atgff:CommingledFundsMember atgff:PostRetirementBenefitsMember us-gaap:DefinedBenefitPlanEquitySecuritiesLargeCapMember 2022-12-31 0001695519 atgff:WglHoldingsMember us-gaap:ForeignPlanMember atgff:CommingledFundsMember atgff:PostRetirementBenefitsMember us-gaap:DefinedBenefitPlanEquitySecuritiesLargeCapMember 2021-12-31 0001695519 atgff:WglHoldingsMember us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FixedIncomeSecuritiesMember 2022-12-31 0001695519 atgff:WglHoldingsMember us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember us-gaap:FixedIncomeSecuritiesMember 2021-12-31 0001695519 atgff:WglHoldingsMember us-gaap:CorporateBondSecuritiesMember us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember 2022-12-31 0001695519 atgff:WglHoldingsMember us-gaap:CorporateBondSecuritiesMember us-gaap:ForeignPlanMember atgff:PostRetirementBenefitsMember 2021-12-31 0001695519 atgff:DefinedBenefitPlanMember srt:MinimumMember 2022-01-01 2022-12-31 0001695519 srt:MaximumMember atgff:DefinedBenefitPlanMember 2022-01-01 2022-12-31 0001695519 srt:MaximumMember atgff:PostRetirementBenefitsMember 2022-01-01 2022-12-31 0001695519 atgff:DefinedBenefitPlanMember srt:MinimumMember 2021-01-01 2021-12-31 0001695519 srt:MaximumMember atgff:DefinedBenefitPlanMember 2021-01-01 2021-12-31 0001695519 atgff:PostRetirementBenefitsMember srt:MinimumMember 2021-01-01 2021-12-31 0001695519 srt:MaximumMember atgff:PostRetirementBenefitsMember 2021-01-01 2021-12-31 0001695519 atgff:PostRetirementBenefitsMember srt:MinimumMember 2022-01-01 2022-12-31 0001695519 atgff:DefinedBenefitPlanMember srt:MinimumMember 2022-12-31 0001695519 srt:MaximumMember atgff:DefinedBenefitPlanMember 2022-12-31 0001695519 atgff:PostRetirementBenefitsMember srt:MinimumMember 2022-12-31 0001695519 srt:MaximumMember atgff:PostRetirementBenefitsMember 2022-12-31 0001695519 atgff:DefinedBenefitPlanMember srt:MinimumMember 2021-12-31 0001695519 srt:MaximumMember atgff:DefinedBenefitPlanMember 2021-12-31 0001695519 srt:MaximumMember atgff:PostRetirementBenefitsMember 2021-12-31 0001695519 srt:MinimumMember 2022-12-31 0001695519 srt:NaturalGasReservesMember 2022-12-31 0001695519 atgff:StorageServicesMember 2022-12-31 0001695519 us-gaap:PublicUtilitiesInventoryPropaneMember 2022-12-31 0001695519 us-gaap:ElectricityPurchasedMember 2022-12-31 0001695519 atgff:OperatingLeaseContractsMember 2022-12-31 0001695519 atgff:ServiceAgreementMember 2022-12-31 0001695519 atgff:EnvironmentalCommitmentsMember 2022-12-31 0001695519 atgff:PostAcquisitionContingentPaymentsMember 2022-12-31 0001695519 atgff:CrudeOilAndCondensatePurchaseMember 2022-12-31 0001695519 atgff:MergerCommitmentsMember 2022-12-31 0001695519 atgff:CapitalProjectsMember 2022-12-31 0001695519 atgff:ElectricityRenewableEnergyCreditsMember 2022-12-31 0001695519 atgff:VeryLargeGasCarriersMember 2022-12-31 0001695519 atgff:ServiceAgreementMember 2014-01-01 2014-12-31 atgff:hour 0001695519 atgff:ServiceAgreementMember 2017-01-01 2017-12-31 0001695519 atgff:RidleyTerminalsInc.Member atgff:ServiceAgreementMember 2015-12-31 0001695519 us-gaap:IntersegmentEliminationMember atgff:UtilitiesSegmentMember 2021-01-01 2021-12-31 0001695519 us-gaap:IntersegmentEliminationMember atgff:MidstreamSegmentMember 2021-01-01 2021-12-31 0001695519 atgff:CorporateAndOtherSegmentMember us-gaap:IntersegmentEliminationMember 2021-01-01 2021-12-31 0001695519 us-gaap:IntersegmentEliminationMember 2021-01-01 2021-12-31 0001695519 us-gaap:OperatingSegmentsMember 2021-01-01 2021-12-31 0001695519 country:CA 2022-01-01 2022-12-31 0001695519 country:CA 2021-01-01 2021-12-31 0001695519 country:US 2022-01-01 2022-12-31 0001695519 country:US 2021-01-01 2021-12-31 0001695519 country:CA 2022-12-31 0001695519 country:CA 2021-12-31 0001695519 country:US 2022-12-31 0001695519 country:US 2021-12-31 0001695519 us-gaap:IntersegmentEliminationMember 2022-01-01 2022-12-31 0001695519 atgff:UtilitiesSegmentMember us-gaap:OperatingSegmentsMember 2022-12-31 0001695519 us-gaap:OperatingSegmentsMember atgff:MidstreamSegmentMember 2022-12-31 0001695519 atgff:CorporateAndOtherSegmentMember us-gaap:OperatingSegmentsMember 2022-12-31 0001695519 atgff:UtilitiesSegmentMember us-gaap:OperatingSegmentsMember 2021-12-31 0001695519 us-gaap:OperatingSegmentsMember atgff:MidstreamSegmentMember 2021-12-31 0001695519 atgff:CorporateAndOtherSegmentMember us-gaap:OperatingSegmentsMember 2021-12-31 0001695519 us-gaap:SubsequentEventMember atgff:ENSTARMember 2023-03-01 0001695519 us-gaap:SubsequentEventMember atgff:CINGSAMember 2023-03-01 0001695519 us-gaap:SubsequentEventMember 2023-03-01 2023-03-01
U.S. SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549
FORM 40-F
☐ REGISTRATION STATEMENT PURSUANT TO SECTION 12 OF THE SECURITIES EXCHANGE ACT OF 1934.
☒ ANNUAL REPORT PURSUANT TO SECTION 13(a) or 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
For the fiscal year ended:
December 31 , 2022Commission File Number:
333-225606
ALTAGAS LTD.
(Exact name of Registrant as specified in its charter)
Canada
(Province or other jurisdiction of incorporation or organization)
1311
Not Applicable
(Primary Standard Industrial
Classification Code Number)
(I.R.S. Employer
Identification Number)
1700, 355-4 th Avenue S.W .
Calgary , Alberta T2P 0J1, Canada
(403 ) 691-7575
(Address and telephone number of Registrant’s principal executive offices)
AltaGas Services (U.S.) Inc.
1000 Maine Ave.
Washington DC 20024
(703 ) 750-4400
(Name, address (including zip code) and telephone number (including area code)
of agent for service in the United States)
Securities registered or to be registered pursuant to Section 12(b) of the Act.
None
(Title of Class)
Securities registered or to be registered pursuant to Section 12(g) of the Act.
None
(Title of Class)
Securities for which there is a reporting obligation pursuant to Section 15(d) of the Act.
None
(Title of Class)
For Annual Reports indicate by check mark the information filed with this Form:
☒ Annual information form
☒ Audited annual financial statements
Indicate the number of outstanding shares of each of the issuer’s classes of capital or common stock as of the close of the period covered by the annual report:
There were 281,531,833 Common Shares, of no par value, outstanding as of December 31, 2022.
Indicate by check mark whether the Registrant (1) has filed all reports to be filed by Section 13 or 15(d) of the Exchange Act during the preceding 12 months (or for such shorter period that the Registrant was required to file such reports) and (2) has been subject to filing requirements for the past 90 days.
Yes ☒ No o
Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the Registrant was required to submit and post such files).
Yes ☒ No o
Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 12b-2 of the Exchange Act.
Emerging growth company ☐
If an emerging growth company that prepares its financial statements in accordance with U.S. GAAP, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐
Indicate by check mark whether the Registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report. ☐
This Annual Report on Form 40-F shall be incorporated by reference into or as an exhibit to, as applicable, the Registrant’s Registration Statement on Form F-10 (File No. 333-253122) and under the Securities Act of 1933, as amended ("Securities Act").
PRINCIPAL DOCUMENTS
The following documents have been filed as part of this Annual Report on Form 40-F as Exhibits hereto and are incorporated by reference herein:
A. Annual Information Form
The Annual Information Form of AltaGas Ltd. (the “Registrant”) for the fiscal year ended December 31, 2022 is included as Exhibit 13.1 of this Annual Report on Form 40-F.
B. Management's Discussion and Analysis and Audited Annual Financial Statements
The Registrant’s Management’s Discussion and Analysis for the year ended December 31, 2022 and audited consolidated financial statements for the fiscal year ended December 31, 2022, including the auditor’s report with respect thereto, are included as Exhibit 13.2 of this Annual Report on Form 40-F.
CERTIFICATIONS AND DISCLOSURE REGARDING CONTROLS AND PROCEDURES
Certifications . See Exhibits 31.1, 31.2, 32.1, and 32.2 to this Annual Report on Form 40-F.
Disclosure Controls and Procedures . The Registrant maintains disclosure controls and procedures and internal control over financial reporting designed to ensure that information required to be disclosed in the Registrant’s filings under the Securities Exchange Act of 1934, as amended ("Exchange Act") is recorded, processed, summarized and reported within the time periods specified in the rules and forms of the Securities and Exchange Commission (the “Commission”). The Registrant’s Chief Executive Officer (“CEO”) and Chief Financial Officer (“CFO”), after having evaluated the effectiveness of the Registrant’s disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) as of the end of the period covered by this Annual Report on Form 40-F, have concluded that, as of such date, the Registrant’s disclosure controls and procedures were effective to ensure that information required to be disclosed by the Registrant in reports that the Registrant files or submits under the Exchange Act is (i) recorded, processed, summarized and reported, within the time periods specified in the Commission’s rules and forms, and (ii) accumulated and communicated to management, including its principal executive and principal financial officers, or persons performing similar functions, as appropriate to allow timely decisions regarding required disclosure. However, as recommended by the Commission in its adopting release for the rules governing the disclosure and control procedures discussed above, the Registrant will continue to periodically evaluate its disclosure controls and procedures and will make modifications from time to time as deemed necessary to ensure that information is recorded, processed, summarized and reported within the time periods specified in the Commission’s rules and forms.
The Registrant’s disclosure controls and procedures are designed to provide reasonable assurance of achieving their objectives, and, as indicated in the preceding paragraph, the CEO and CFO believe that the Registrant’s disclosure controls and procedures are effective at that reasonable assurance level, although the CEO and CFO do not expect that the disclosure controls and procedures or internal control over financial reporting will prevent all errors and fraud. A control system, no matter how well conceived or operated, can provide only reasonable, not absolute, assurance that the objectives of the control system are met.
Management Report on Internal Control over Financial Reporting: The Registrant’s management is responsible for establishing and maintaining adequate internal control over financial reporting. The Registrant’s internal control framework is based on the criteria published in the 2013 Internal Control – Integrated Framework issued by the Committee of Sponsoring Organizations (COSO) of the Treadway Commission. The Registrant’s management, including the CEO and CFO, evaluated the effectiveness of the Registrant’s internal control over financial reporting as at December 31, 2022 and concluded that the Registrant’s internal control over financial reporting is effective as at December 31, 2022.
Auditor’s Attestation Report: This annual report does not include an attestation report of the Registrant's registered public accounting firm regarding internal control over financial reporting. Management’s report was not subject to attestation by the Registrant's registered public accounting firm pursuant to the Dodd-Frank Wall Street Reform and Consumer Protection Act of 2010 (the “ Dodd-Frank Act ”). The Dodd-Frank Act permits a “non-accelerated filer” to provide only management's report on internal control over financial reporting in an annual report and omit an attestation report of the issuer's registered public accounting firm regarding management's report on internal control over financial reporting.
Changes in Internal Control Over Financial Reporting: During the fiscal year ended December 31, 2022, there were no changes in the Registrant’s internal control over financial reporting that have materially affected, or are reasonably likely to materially affect, the Registrant’s internal control over financial reporting.
NOTICES PURSUANT TO REGULATION BTR
None.
IDENTIFICATION OF THE AUDIT COMMITTEE
The Registrant has a separately-designated standing audit committee (the "Audit Committee") established in accordance with Section 3(a)(58)(A) of the Exchange Act. The members of the Audit Committee are: Linda G. Sullivan, Robert B. Hodgins, Cynthia Johnston, and Nancy G. Tower.
AUDIT COMMITTEE FINANCIAL EXPERTS
The board of directors of the Registrant has determined that Linda G. Sullivan, the chair of the Audit Committee, qualifies as an audit committee financial expert for purposes of paragraph (8) of General Instruction B to Form 40-F. Details of her relevant experience is included under the heading “Audit Committee - Relevant Education and Experience” at page 49 of the Registrant’s Annual Information Form for the fiscal year ended December 31, 2022, filed as part of this Annual Report on Form 40-F in Exhibit 13.1. The Commission has indicated that the designation of Linda G. Sullivan as an audit committee financial expert does not (i) make her an “expert” for any purpose, including without limitation for purposes of Section 11 of the Securities Act, (ii) impose on her any duties, obligations or liabilities that are greater than those imposed on members of the Audit Committee and the board of directors who do not carry this designation or identification or (iii) affect the duties, obligations or liabilities of any other member of the Audit Committee or the board of directors. The board of directors has
further determined that each of Linda G. Sullivan, Robert B. Hodgins, Cynthia Johnston, and Nancy G. Tower is independent, as that term is defined in the Corporate Governance Listing Standards of the New York Stock Exchange.
ADDITIONAL DISCLOSURE
Code of Ethics
The Registrant has adopted a “code of ethics” (as that term is defined in paragraph (9) of General Instruction B to Form 40-F), entitled the “Code of Business Ethics”, that applies to directors, officers, employees, contractors, consultants, representatives and agents of the Registrant including its principal executive officer, principal financial officer, principal accounting officer or controller, and persons performing similar functions. During the fiscal year ended December 31, 2022, there were no waivers, including implicit waivers, or amendments granted from any provision of the Code of Business Ethics.
The Code of Business Ethics is available for viewing on the Registrant’s website at www.altagas.ca.
Principal Accountant Fees and Services
The Registrant’s auditor is Ernst & Young LLP (Calgary, AB, Canada , PCAOB ID: 01263 ).
The required disclosure is included under the heading “Audit Committee - External Auditor Service Fees by Category” at page 50 of the Registrant’s Annual Information Form for the fiscal year ended December 31, 2022, filed as part of this Annual Report on Form 40-F in Exhibit 13.1.
Pre-Approval Policies and Procedures
The Audit Committee pre-approves all audit services to be provided to the Registrant by its independent auditors. The Audit Committee’s policy regarding the pre-approval of non-audit services to be provided to the Registrant by its independent auditors is that all such services shall be pre-approved by the Audit Committee. All non-audit services performed by the Registrant's independent auditors for the fiscal year ended December 31, 2022 have been pre-approved by the Audit Committee.
Off-Balance Sheet Arrangements
The Registrant has no off-balance sheet arrangements as described in paragraph (11) of General Instruction B to Form 40-F.
Tabular Disclosure of Contractual Obligations
The required disclosure is included under the heading “Contractual Obligations” in the Registrant’s Management’s Discussion and Analysis for the year ended December 31, 2022, filed as part of this Annual Report on Form 40-F in Exhibit 13.2.
Mine Safety Disclosure.
Not applicable.
UNDERTAKING
The Registrant undertakes to make available, in person or by telephone, representatives to respond to inquiries made by the Commission staff, and to furnish promptly, when requested to do so by the Commission staff, information relating to: the securities registered pursuant to Form 40-F; the securities in relation to which the obligation to file an annual report on Form 40-F arises; or transactions in said securities.
CONSENT TO SERVICE OF PROCESS
The Registrant has previously filed with the Commission a Form F-X in connection with the class of securities in relation to which the obligation to file this report arises.
Any changes to the name or address of the agent for service of process of the Registrant shall be communicated promptly to the Commission by an amendment to the Form F-X referencing the file number of the Registrant.
SIGNATURES
Pursuant to the requirements of the Exchange Act, the Registrant certifies that it meets all of the requirements for filing on Form 40-F and has duly caused this Annual Report to be signed on its behalf by the undersigned, thereunto duly authorized.
Date: March 2, 2023
AltaGas Ltd. By: /s/ Randall L. Crawford Name: Randall L. Crawford Title: President and Chief Executive Officer
EXHIBIT INDEX
13.1 13.2 23.1 31.1 31.2 32.1 32.2 101 Interactive Data File