false--09-30FY201900000701450.630.670.71000245370002578800001.641.681.7211200000000200000000859568148631528785956814863152870.0520.03750.0740.0520.03750.0741.011.0110000000.0450.045100000100000000000020000000235700021340002532000P1YP1YP1YP1YP1Y000000000 0000070145 2018-10-01 2019-09-30 0000070145 2019-03-31 0000070145 2019-10-31 0000070145 2017-10-01 2018-09-30 0000070145 us-gaap:AccountingStandardsUpdate201802Member 2016-10-01 2017-09-30 0000070145 nfg:ExplorationandProductionandOtherCategoryMember 2018-10-01 2019-09-30 0000070145 2017-09-30 0000070145 2016-10-01 2017-09-30 0000070145 us-gaap:AccountingStandardsUpdate201601Member 2018-10-01 2019-09-30 0000070145 nfg:PipelineandStorageandGatheringMember 2016-10-01 2017-09-30 0000070145 us-gaap:AccountingStandardsUpdate201802Member 2018-10-01 2019-09-30 0000070145 2016-09-30 0000070145 nfg:PipelineandStorageandGatheringMember 2017-10-01 2018-09-30 0000070145 us-gaap:OilAndGasPurchasedMember 2016-10-01 2017-09-30 0000070145 us-gaap:AccountingStandardsUpdate201609Member 2018-10-01 2019-09-30 0000070145 2019-09-30 0000070145 nfg:UtilityandEnergyMarketingMember 2017-10-01 2018-09-30 0000070145 us-gaap:AccountingStandardsUpdate201601Member 2017-10-01 2018-09-30 0000070145 us-gaap:AccountingStandardsUpdate201601Member 2016-10-01 2017-09-30 0000070145 nfg:UtilityandEnergyMarketingMember 2018-10-01 2019-09-30 0000070145 nfg:ExplorationandProductionandOtherCategoryMember 2016-10-01 2017-09-30 0000070145 nfg:ExplorationandProductionandOtherCategoryMember 2017-10-01 2018-09-30 0000070145 us-gaap:AccountingStandardsUpdate201609Member 2016-10-01 2017-09-30 0000070145 2018-09-30 0000070145 nfg:UtilityandEnergyMarketingMember 2016-10-01 2017-09-30 0000070145 us-gaap:OilAndGasPurchasedMember 2017-10-01 2018-09-30 0000070145 nfg:PipelineandStorageandGatheringMember 2018-10-01 2019-09-30 0000070145 us-gaap:AccountingStandardsUpdate201609Member 2017-10-01 2018-09-30 0000070145 us-gaap:AccountingStandardsUpdate201802Member 2017-10-01 2018-09-30 0000070145 us-gaap:OilAndGasPurchasedMember 2018-10-01 2019-09-30 0000070145 nfg:GatheringMember 2016-10-01 2017-09-30 0000070145 nfg:PipelineAndStorageMember 2018-10-01 2019-09-30 0000070145 nfg:UtilityMember 2017-10-01 2018-09-30 0000070145 nfg:PipelineAndStorageMember 2017-10-01 2018-09-30 0000070145 nfg:AllOtherAndCorporateMember 2018-10-01 2019-09-30 0000070145 nfg:GatheringMember 2018-10-01 2019-09-30 0000070145 nfg:GatheringMember 2017-10-01 2018-09-30 0000070145 nfg:UtilityMember 2016-10-01 2017-09-30 0000070145 nfg:AllOtherAndCorporateMember 2017-10-01 2018-09-30 0000070145 nfg:AllOtherAndCorporateMember 2016-10-01 2017-09-30 0000070145 nfg:UtilityMember 2018-10-01 2019-09-30 0000070145 nfg:PipelineAndStorageMember 2016-10-01 2017-09-30 0000070145 nfg:ExplorationAndProductionMember 2017-10-01 2018-09-30 0000070145 nfg:ExplorationAndProductionMember 2016-10-01 2017-09-30 0000070145 nfg:ExplorationAndProductionMember 2018-10-01 2019-09-30 0000070145 nfg:PipelineAndStorageMember 2018-09-30 0000070145 nfg:PipelineAndStorageMember 2019-09-30 0000070145 nfg:UtilityMember 2018-09-30 0000070145 nfg:ExplorationAndProductionMember 2018-09-30 0000070145 nfg:UtilityMember 2019-09-30 0000070145 nfg:AllOtherAndCorporateMember 2019-09-30 0000070145 nfg:GatheringMember 2019-09-30 0000070145 nfg:ExplorationAndProductionMember 2019-09-30 0000070145 nfg:GatheringMember 2018-09-30 0000070145 nfg:AllOtherAndCorporateMember 2018-09-30 0000070145 nfg:SenecaMember 2016-10-01 2017-09-30 0000070145 nfg:AccumulatedLossesMember 2018-09-30 0000070145 nfg:AccumulatedLossesMember 2019-09-30 0000070145 nfg:SespeFieldMember 2017-10-01 2018-09-30 0000070145 nfg:LifoMethodMember 2019-09-30 0000070145 srt:ScenarioForecastMember us-gaap:AccountingStandardsUpdate201602Member 2019-10-01 0000070145 nfg:OilAndGasProducingPropertiesMember 2017-10-01 2018-09-30 0000070145 us-gaap:AccountingStandardsUpdate201802Member 2019-09-30 0000070145 srt:ScenarioForecastMember us-gaap:AccountingStandardsUpdate201712Member 2019-10-01 0000070145 nfg:AmountExceedsLifoBasisMember 2019-09-30 0000070145 nfg:OilAndGasProducingPropertiesMember 2016-10-01 2017-09-30 0000070145 nfg:OilAndGasProducingPropertiesMember 2018-10-01 2019-09-30 0000070145 nfg:SenecaMember 2017-10-01 2018-09-30 0000070145 nfg:SespeFieldMember 2017-10-01 2017-10-31 0000070145 us-gaap:AccountingStandardsUpdate201601Member 2019-09-30 0000070145 nfg:UnamortizedDebtExpenseMember 2018-10-01 2019-09-30 0000070145 us-gaap:StateAndLocalJurisdictionMember 2018-09-30 0000070145 us-gaap:InternalRevenueServiceIRSMember 2018-09-30 0000070145 us-gaap:InternalRevenueServiceIRSMember 2019-09-30 0000070145 us-gaap:StateAndLocalJurisdictionMember 2019-09-30 0000070145 nfg:AccruedCapitalExpendituresMember 2018-09-30 0000070145 nfg:RegulatoryLiabilitiesMember 2019-09-30 0000070145 nfg:CurrentMember us-gaap:NonqualifiedPlanMember 2018-09-30 0000070145 nfg:OtherAccrualsMember 2018-09-30 0000070145 nfg:CurrentMember us-gaap:NonqualifiedPlanMember 2019-09-30 0000070145 nfg:AccruedCapitalExpendituresMember 2019-09-30 0000070145 nfg:OtherAccrualsMember 2019-09-30 0000070145 nfg:RegulatoryLiabilitiesMember 2018-09-30 0000070145 us-gaap:AccumulatedDefinedBenefitPlansAdjustmentMember 2018-10-01 2019-09-30 0000070145 us-gaap:AccumulatedNetUnrealizedInvestmentGainLossMember 2018-10-01 2019-09-30 0000070145 us-gaap:AccumulatedDefinedBenefitPlansAdjustmentMember 2017-10-01 2018-09-30 0000070145 us-gaap:AccumulatedNetUnrealizedInvestmentGainLossMember 2018-09-30 0000070145 us-gaap:AccumulatedDefinedBenefitPlansAdjustmentMember 2018-09-30 0000070145 us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember 2018-10-01 2019-09-30 0000070145 us-gaap:AccumulatedDefinedBenefitPlansAdjustmentMember 2019-09-30 0000070145 us-gaap:AccumulatedDefinedBenefitPlansAdjustmentMember 2017-09-30 0000070145 us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember 2019-09-30 0000070145 us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember 2018-09-30 0000070145 us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember 2017-10-01 2018-09-30 0000070145 us-gaap:AccumulatedNetUnrealizedInvestmentGainLossMember 2017-09-30 0000070145 us-gaap:AccumulatedNetUnrealizedInvestmentGainLossMember 2019-09-30 0000070145 us-gaap:AccumulatedNetUnrealizedInvestmentGainLossMember 2017-10-01 2018-09-30 0000070145 us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember 2017-09-30 0000070145 us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember 2017-10-01 2018-09-30 0000070145 us-gaap:OilAndGasPurchasedMember us-gaap:CommodityContractMember us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember 2017-10-01 2018-09-30 0000070145 us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember us-gaap:AccumulatedDefinedBenefitPlansAdjustmentMember 2018-10-01 2019-09-30 0000070145 us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember 2018-10-01 2019-09-30 0000070145 us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember us-gaap:AccumulatedNetUnrealizedInvestmentGainLossMember 2017-10-01 2018-09-30 0000070145 us-gaap:ForeignExchangeContractMember us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember 2017-10-01 2018-09-30 0000070145 us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember us-gaap:AccumulatedDefinedBenefitPlansAdjustmentMember 2017-10-01 2018-09-30 0000070145 us-gaap:OilAndGasPurchasedMember us-gaap:CommodityContractMember us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember 2018-10-01 2019-09-30 0000070145 us-gaap:ForeignExchangeContractMember us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember 2018-10-01 2019-09-30 0000070145 us-gaap:CommodityContractMember us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember 2018-10-01 2019-09-30 0000070145 us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember us-gaap:AccumulatedNetUnrealizedInvestmentGainLossMember 2018-10-01 2019-09-30 0000070145 us-gaap:CommodityContractMember us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember 2017-10-01 2018-09-30 0000070145 us-gaap:OilAndGasServiceMember nfg:AllOtherMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasProcessingMember nfg:CorporateAndIntersegmentEliminationsMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasCommercialSalesMember nfg:GatheringMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasResidentialSalesMember nfg:CorporateAndIntersegmentEliminationsMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasResidentialSalesMember nfg:AllOtherMember 2018-10-01 2019-09-30 0000070145 us-gaap:ConsolidatedEntitiesMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasProcessingMember nfg:GatheringMember 2018-10-01 2019-09-30 0000070145 us-gaap:NaturalGasStorageMember nfg:PipelineAndStorageMember 2018-10-01 2019-09-30 0000070145 nfg:TotalReportableSegmentsMember 2018-10-01 2019-09-30 0000070145 nfg:ProductionofCrudeOilMember nfg:GatheringMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasProcessingMember nfg:ExplorationAndProductionMember 2018-10-01 2019-09-30 0000070145 us-gaap:ProductAndServiceOtherMember nfg:UtilityMember 2018-10-01 2019-09-30 0000070145 us-gaap:NaturalGasMidstreamMember us-gaap:ConsolidatedEntitiesMember 2018-10-01 2019-09-30 0000070145 us-gaap:ProductAndServiceOtherMember us-gaap:ConsolidatedEntitiesMember 2018-10-01 2019-09-30 0000070145 nfg:AllOtherMember 2018-10-01 2019-09-30 0000070145 us-gaap:NaturalGasProductionMember nfg:PipelineAndStorageMember 2018-10-01 2019-09-30 0000070145 us-gaap:NaturalGasProductionMember nfg:UtilityMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasResidentialSalesMember nfg:GatheringMember 2018-10-01 2019-09-30 0000070145 us-gaap:OilAndGasServiceMember nfg:CorporateAndIntersegmentEliminationsMember 2018-10-01 2019-09-30 0000070145 us-gaap:ProductAndServiceOtherMember nfg:GatheringMember 2018-10-01 2019-09-30 0000070145 us-gaap:NaturalGasStorageMember nfg:CorporateAndIntersegmentEliminationsMember 2018-10-01 2019-09-30 0000070145 us-gaap:ProductAndServiceOtherMember nfg:CorporateAndIntersegmentEliminationsMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasCommercialSalesMember nfg:AllOtherMember 2018-10-01 2019-09-30 0000070145 us-gaap:OilAndGasServiceMember us-gaap:ConsolidatedEntitiesMember 2018-10-01 2019-09-30 0000070145 us-gaap:OilAndGasServiceMember nfg:UtilityMember 2018-10-01 2019-09-30 0000070145 nfg:ProductionofCrudeOilMember nfg:ExplorationAndProductionMember 2018-10-01 2019-09-30 0000070145 us-gaap:ProductAndServiceOtherMember nfg:ExplorationAndProductionMember 2018-10-01 2019-09-30 0000070145 us-gaap:OilAndGasRefiningAndMarketingMember us-gaap:ConsolidatedEntitiesMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasResidentialSalesMember nfg:PipelineAndStorageMember 2018-10-01 2019-09-30 0000070145 us-gaap:NaturalGasProductionMember us-gaap:ConsolidatedEntitiesMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasResidentialSalesMember nfg:TotalReportableSegmentsMember 2018-10-01 2019-09-30 0000070145 nfg:CorporateAndIntersegmentEliminationsMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasResidentialSalesMember us-gaap:ConsolidatedEntitiesMember 2018-10-01 2019-09-30 0000070145 us-gaap:NaturalGasStorageMember us-gaap:ConsolidatedEntitiesMember 2018-10-01 2019-09-30 0000070145 us-gaap:NaturalGasStorageMember nfg:UtilityMember 2018-10-01 2019-09-30 0000070145 us-gaap:NaturalGasStorageMember nfg:ExplorationAndProductionMember 2018-10-01 2019-09-30 0000070145 us-gaap:NaturalGasMidstreamMember nfg:TotalReportableSegmentsMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasResidentialSalesMember nfg:ExplorationAndProductionMember 2018-10-01 2019-09-30 0000070145 us-gaap:OilAndGasRefiningAndMarketingMember nfg:CorporateAndIntersegmentEliminationsMember 2018-10-01 2019-09-30 0000070145 us-gaap:OilAndGasRefiningAndMarketingMember nfg:TotalReportableSegmentsMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasProcessingMember nfg:UtilityMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasResidentialSalesMember nfg:UtilityMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasProcessingMember nfg:AllOtherMember 2018-10-01 2019-09-30 0000070145 us-gaap:OilAndGasServiceMember nfg:GatheringMember 2018-10-01 2019-09-30 0000070145 us-gaap:NaturalGasMidstreamMember nfg:PipelineAndStorageMember 2018-10-01 2019-09-30 0000070145 us-gaap:OilAndGasServiceMember nfg:TotalReportableSegmentsMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasIndustrialSalesMember nfg:GatheringMember 2018-10-01 2019-09-30 0000070145 us-gaap:NaturalGasStorageMember nfg:AllOtherMember 2018-10-01 2019-09-30 0000070145 us-gaap:OilAndGasRefiningAndMarketingMember nfg:UtilityMember 2018-10-01 2019-09-30 0000070145 us-gaap:OilAndGasRefiningAndMarketingMember nfg:PipelineAndStorageMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasCommercialSalesMember nfg:PipelineAndStorageMember 2018-10-01 2019-09-30 0000070145 us-gaap:NaturalGasStorageMember nfg:GatheringMember 2018-10-01 2019-09-30 0000070145 us-gaap:OilAndGasServiceMember nfg:ExplorationAndProductionMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasCommercialSalesMember nfg:UtilityMember 2018-10-01 2019-09-30 0000070145 us-gaap:NaturalGasMidstreamMember nfg:UtilityMember 2018-10-01 2019-09-30 0000070145 us-gaap:NaturalGasMidstreamMember nfg:AllOtherMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasCommercialSalesMember nfg:ExplorationAndProductionMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasIndustrialSalesMember nfg:AllOtherMember 2018-10-01 2019-09-30 0000070145 us-gaap:NaturalGasProductionMember nfg:ExplorationAndProductionMember 2018-10-01 2019-09-30 0000070145 nfg:ProductionofCrudeOilMember nfg:PipelineAndStorageMember 2018-10-01 2019-09-30 0000070145 us-gaap:NaturalGasProductionMember nfg:TotalReportableSegmentsMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasProcessingMember nfg:PipelineAndStorageMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasCommercialSalesMember nfg:CorporateAndIntersegmentEliminationsMember 2018-10-01 2019-09-30 0000070145 us-gaap:NaturalGasMidstreamMember nfg:CorporateAndIntersegmentEliminationsMember 2018-10-01 2019-09-30 0000070145 nfg:ProductionofCrudeOilMember nfg:AllOtherMember 2018-10-01 2019-09-30 0000070145 us-gaap:ProductAndServiceOtherMember nfg:TotalReportableSegmentsMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasIndustrialSalesMember nfg:ExplorationAndProductionMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasProcessingMember us-gaap:ConsolidatedEntitiesMember 2018-10-01 2019-09-30 0000070145 nfg:ProductionofCrudeOilMember nfg:UtilityMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasIndustrialSalesMember nfg:UtilityMember 2018-10-01 2019-09-30 0000070145 us-gaap:NaturalGasProductionMember nfg:GatheringMember 2018-10-01 2019-09-30 0000070145 us-gaap:NaturalGasMidstreamMember nfg:GatheringMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasCommercialSalesMember nfg:TotalReportableSegmentsMember 2018-10-01 2019-09-30 0000070145 nfg:ProductionofCrudeOilMember us-gaap:ConsolidatedEntitiesMember 2018-10-01 2019-09-30 0000070145 nfg:ProductionofCrudeOilMember nfg:TotalReportableSegmentsMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasIndustrialSalesMember us-gaap:ConsolidatedEntitiesMember 2018-10-01 2019-09-30 0000070145 us-gaap:ProductAndServiceOtherMember nfg:PipelineAndStorageMember 2018-10-01 2019-09-30 0000070145 us-gaap:OilAndGasRefiningAndMarketingMember nfg:ExplorationAndProductionMember 2018-10-01 2019-09-30 0000070145 us-gaap:OilAndGasServiceMember nfg:PipelineAndStorageMember 2018-10-01 2019-09-30 0000070145 us-gaap:NaturalGasMidstreamMember nfg:ExplorationAndProductionMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasProcessingMember nfg:TotalReportableSegmentsMember 2018-10-01 2019-09-30 0000070145 nfg:ProductionofCrudeOilMember nfg:CorporateAndIntersegmentEliminationsMember 2018-10-01 2019-09-30 0000070145 us-gaap:OilAndGasRefiningAndMarketingMember nfg:GatheringMember 2018-10-01 2019-09-30 0000070145 us-gaap:NaturalGasProductionMember nfg:AllOtherMember 2018-10-01 2019-09-30 0000070145 us-gaap:ProductAndServiceOtherMember nfg:AllOtherMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasIndustrialSalesMember nfg:CorporateAndIntersegmentEliminationsMember 2018-10-01 2019-09-30 0000070145 us-gaap:NaturalGasProductionMember nfg:CorporateAndIntersegmentEliminationsMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasCommercialSalesMember us-gaap:ConsolidatedEntitiesMember 2018-10-01 2019-09-30 0000070145 us-gaap:OilAndGasRefiningAndMarketingMember nfg:AllOtherMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasIndustrialSalesMember nfg:TotalReportableSegmentsMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasIndustrialSalesMember nfg:PipelineAndStorageMember 2018-10-01 2019-09-30 0000070145 us-gaap:NaturalGasStorageMember nfg:TotalReportableSegmentsMember 2018-10-01 2019-09-30 0000070145 2020-10-01 2019-09-30 0000070145 2022-10-01 2019-09-30 0000070145 2019-10-01 2019-09-30 0000070145 2023-10-01 2019-09-30 0000070145 2024-10-01 2019-09-30 0000070145 2021-10-01 2019-09-30 0000070145 nfg:TaxesRefundableToCustomersMember 2018-09-30 0000070145 us-gaap:PostretirementBenefitCostsMember 2018-09-30 0000070145 nfg:TaxesRefundableToCustomersMember 2019-09-30 0000070145 nfg:NonCurrentRegulatoryLiabilitiesMember 2018-09-30 0000070145 us-gaap:PostretirementBenefitCostsMember 2019-09-30 0000070145 nfg:CostOfRemovalRegulatoryLiabilityMember 2018-09-30 0000070145 nfg:AmountsPayableToCustomersMember 2019-09-30 0000070145 nfg:AmountsPayableToCustomersMember 2018-09-30 0000070145 nfg:NonCurrentRegulatoryLiabilitiesMember 2019-09-30 0000070145 nfg:CostOfRemovalRegulatoryLiabilityMember 2019-09-30 0000070145 us-gaap:OtherRegulatoryAssetsLiabilitiesMember 2018-09-30 0000070145 us-gaap:OtherRegulatoryAssetsLiabilitiesMember 2019-09-30 0000070145 nfg:LongTermRegulatoryAssetsMember 2019-09-30 0000070145 us-gaap:AssetRetirementObligationCostsMember 2019-09-30 0000070145 nfg:UnamortizedDebtExpenseMember 2018-09-30 0000070145 nfg:RecoverableFutureTaxesMember 2018-09-30 0000070145 us-gaap:PensionCostsMember 2019-09-30 0000070145 nfg:LongTermRegulatoryAssetsMember 2018-09-30 0000070145 us-gaap:OtherRegulatoryAssetsLiabilitiesMember 2019-09-30 0000070145 nfg:UnamortizedDebtExpenseMember 2019-09-30 0000070145 nfg:RecoverableFutureTaxesMember 2019-09-30 0000070145 us-gaap:OtherRegulatoryAssetsLiabilitiesMember 2018-09-30 0000070145 us-gaap:AssetRetirementObligationCostsMember 2018-09-30 0000070145 us-gaap:EnvironmentalRestorationCostsMember 2018-09-30 0000070145 us-gaap:EnvironmentalRestorationCostsMember 2019-09-30 0000070145 us-gaap:PostretirementBenefitCostsMember 2018-09-30 0000070145 us-gaap:PensionCostsMember 2018-09-30 0000070145 us-gaap:PostretirementBenefitCostsMember 2019-09-30 0000070145 nfg:SupplyCorporationMember 2018-10-01 2019-09-30 0000070145 nfg:OtherAccrualsAndCurrentLiabilitiesMember 2018-09-30 0000070145 nfg:OtherAccrualsAndCurrentLiabilitiesMember 2019-09-30 0000070145 us-gaap:OtherCurrentAssetsMember 2018-09-30 0000070145 us-gaap:OtherCurrentAssetsMember 2019-09-30 0000070145 us-gaap:PerformanceSharesMember 2018-10-01 2019-09-30 0000070145 us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-10-01 2019-09-30 0000070145 us-gaap:PensionPlansDefinedBenefitMember 2018-10-01 2019-09-30 0000070145 us-gaap:ResearchMember 2019-09-30 0000070145 stpr:CA nfg:AlternativeMinimumTaxCreditMember 2019-09-30 0000070145 us-gaap:InternalRevenueServiceIRSMember us-gaap:GeneralBusinessMember 2019-09-30 0000070145 stpr:CA 2019-09-30 0000070145 stpr:CA us-gaap:GeneralBusinessMember 2019-09-30 0000070145 stpr:PA 2019-09-30 0000070145 us-gaap:InternalRevenueServiceIRSMember nfg:AlternativeMinimumTaxCreditMember 2019-09-30 0000070145 us-gaap:AccountingStandardsUpdate201609Member 2017-09-30 0000070145 nfg:DeferredIncomeTaxesMember 2019-09-30 0000070145 nfg:DeferredIncomeTaxesMember 2018-09-30 0000070145 nfg:AlternativeMinimumTaxCreditMember 2018-09-30 0000070145 2018-01-01 2018-09-30 0000070145 us-gaap:OtherCurrentAssetsMember us-gaap:InternalRevenueServiceIRSMember 2019-09-30 0000070145 us-gaap:PerformanceSharesMember 2018-09-30 0000070145 us-gaap:PerformanceSharesMember 2019-09-30 0000070145 nfg:NonPerformanceRestrictedStockUnitsRsusMember 2019-09-30 0000070145 nfg:NonPerformanceRestrictedStockUnitsRsusMember 2018-10-01 2019-09-30 0000070145 nfg:NonPerformanceRestrictedStockUnitsRsusMember 2018-09-30 0000070145 nfg:A3.75To5.20DueDecember2021ToSeptember2028MemberDomain 2018-09-30 0000070145 nfg:SevenPointFourPercentDueMarchTwoThousandTwentyThreeToJuneTwoThousandTwentyFiveMember 2019-09-30 0000070145 nfg:A3.75To5.20DueDecember2021ToSeptember2028MemberDomain 2019-09-30 0000070145 nfg:SevenPointFourPercentDueMarchTwoThousandTwentyThreeToJuneTwoThousandTwentyFiveMember 2018-09-30 0000070145 us-gaap:StockAppreciationRightsSARSMember 2019-09-30 0000070145 us-gaap:StockAppreciationRightsSARSMember 2018-10-01 2019-09-30 0000070145 us-gaap:StockAppreciationRightsSARSMember 2018-09-30 0000070145 nfg:RestrictedShareAwardsMember 2019-09-30 0000070145 nfg:RestrictedShareAwardsMember 2018-10-01 2019-09-30 0000070145 nfg:RestrictedShareAwardsMember 2018-09-30 0000070145 us-gaap:PerformanceSharesMember 2017-10-01 2018-09-30 0000070145 us-gaap:PerformanceSharesMember 2016-10-01 2017-09-30 0000070145 nfg:NonPerformanceRestrictedStockUnitsRsusMember nfg:TwoThousandTwentyOneMember 2018-10-01 2019-09-30 0000070145 nfg:NonPerformanceRestrictedStockUnitsRsusMember 2016-10-01 2017-09-30 0000070145 nfg:EightPointSevenFivePercentNotesDueMayTwoThousandNineteenMember 2018-09-07 0000070145 nfg:NonPerformanceRestrictedStockUnitsRsusMember nfg:TwoThousandTwentyMember 2018-10-01 2019-09-30 0000070145 us-gaap:StockAppreciationRightsSARSMember 2016-10-01 2017-09-30 0000070145 nfg:NonPerformanceRestrictedStockUnitsRsusMember nfg:TwoThousandTwentyThreeMember 2018-10-01 2019-09-30 0000070145 us-gaap:PerformanceSharesMember nfg:TwoThousandTwentyTwoMember 2018-10-01 2019-09-30 0000070145 nfg:ThreePointNineFivePercentNotesDueSeptemberFifteenTwoThousandTwentySevenMember 2017-09-27 0000070145 us-gaap:PerformanceSharesMember nfg:TwoThousandTwentyOneMember 2018-10-01 2019-09-30 0000070145 nfg:NonPerformanceRestrictedStockUnitsRsusMember nfg:TwoThousandTwentyFourMember 2018-10-01 2019-09-30 0000070145 nfg:NonPerformanceRestrictedStockUnitsRsusMember 2017-10-01 2018-09-30 0000070145 nfg:BoardOfDirectorsMember 2018-10-01 2019-09-30 0000070145 2019-07-01 2019-09-30 0000070145 us-gaap:CommercialPaperMember 2019-09-30 0000070145 nfg:FourPointSevenFivePercentNotesDueSeptemberOneTwoThousandTwentyEightMember 2018-08-17 0000070145 nfg:FourthAmendedRestatedCreditAgreementMember 2019-09-30 0000070145 nfg:RestrictedShareAwardsMember nfg:TwoThousandTwentyOneMember 2018-10-01 2019-09-30 0000070145 us-gaap:StockAppreciationRightsSARSMember 2017-10-01 2018-09-30 0000070145 us-gaap:PerformanceSharesMember nfg:TwoThousandTwentyMember 2018-10-01 2019-09-30 0000070145 nfg:EightPointSevenFivePercentNotesDueMayTwoThousandNineteenMember 2018-09-30 0000070145 nfg:IndentureFrom1974Member 2019-09-30 0000070145 nfg:NonPerformanceRestrictedStockUnitsRsusMember nfg:TwoThousandTwentyTwoMember 2018-10-01 2019-09-30 0000070145 us-gaap:RestrictedStockUnitsRSUMember 2018-10-01 2019-09-30 0000070145 nfg:SixPointFivePercentNotesDueAprilTwoThousandEighteenMember 2018-09-30 0000070145 nfg:FourPointSevenFivePercentNotesDueSeptemberOneTwoThousandTwentyEightMember 2018-08-17 2018-08-17 0000070145 us-gaap:AdditionalPaidInCapitalMember 2017-09-30 0000070145 us-gaap:CommonStockMember 2017-10-01 2018-09-30 0000070145 us-gaap:RetainedEarningsMember 2017-10-01 2018-09-30 0000070145 us-gaap:RetainedEarningsMember 2016-10-01 2017-09-30 0000070145 us-gaap:AdditionalPaidInCapitalMember 2018-10-01 2019-09-30 0000070145 us-gaap:AdditionalPaidInCapitalMember 2018-09-30 0000070145 us-gaap:CommonStockMember 2016-09-30 0000070145 us-gaap:AccumulatedOtherComprehensiveIncomeMember 2018-09-30 0000070145 us-gaap:AdditionalPaidInCapitalMember 2016-10-01 2017-09-30 0000070145 us-gaap:CommonStockMember 2017-09-30 0000070145 us-gaap:RetainedEarningsMember 2018-10-01 2019-09-30 0000070145 us-gaap:AccumulatedOtherComprehensiveIncomeMember 2016-09-30 0000070145 us-gaap:AccumulatedOtherComprehensiveIncomeMember 2018-10-01 2019-09-30 0000070145 us-gaap:CommonStockMember 2018-09-30 0000070145 us-gaap:RetainedEarningsMember 2019-09-30 0000070145 us-gaap:AccumulatedOtherComprehensiveIncomeMember 2016-10-01 2017-09-30 0000070145 us-gaap:AdditionalPaidInCapitalMember 2017-10-01 2018-09-30 0000070145 us-gaap:AccountingStandardsUpdate201802Member us-gaap:RetainedEarningsMember 2019-09-30 0000070145 us-gaap:CommonStockMember 2019-09-30 0000070145 us-gaap:AccountingStandardsUpdate201601Member us-gaap:RetainedEarningsMember 2019-09-30 0000070145 us-gaap:RetainedEarningsMember 2016-09-30 0000070145 us-gaap:CommonStockMember 2016-10-01 2017-09-30 0000070145 us-gaap:AdditionalPaidInCapitalMember 2019-09-30 0000070145 us-gaap:CommonStockMember 2018-10-01 2019-09-30 0000070145 us-gaap:AccumulatedOtherComprehensiveIncomeMember 2017-09-30 0000070145 us-gaap:RetainedEarningsMember 2017-09-30 0000070145 us-gaap:AccumulatedOtherComprehensiveIncomeMember 2017-10-01 2018-09-30 0000070145 us-gaap:AccountingStandardsUpdate201609Member us-gaap:RetainedEarningsMember 2017-09-30 0000070145 us-gaap:AdditionalPaidInCapitalMember 2016-09-30 0000070145 us-gaap:RetainedEarningsMember 2018-09-30 0000070145 us-gaap:AccumulatedOtherComprehensiveIncomeMember 2019-09-30 0000070145 srt:MaximumMember nfg:A3.75To5.20DueDecember2021ToSeptember2028MemberDomain 2019-09-30 0000070145 srt:MaximumMember nfg:A3.75To5.20DueDecember2021ToSeptember2028MemberDomain 2018-09-30 0000070145 nfg:A3.75To5.20DueDecember2021ToSeptember2028MemberDomain 2018-10-01 2019-09-30 0000070145 srt:MinimumMember nfg:A3.75To5.20DueDecember2021ToSeptember2028MemberDomain 2018-09-30 0000070145 nfg:A3.75To5.20DueDecember2021ToSeptember2028MemberDomain 2017-10-01 2018-09-30 0000070145 srt:MinimumMember nfg:A3.75To5.20DueDecember2021ToSeptember2028MemberDomain 2019-09-30 0000070145 nfg:RestrictedShareAwardsMember 2017-10-01 2018-09-30 0000070145 nfg:RestrictedShareAwardsMember 2016-10-01 2017-09-30 0000070145 us-gaap:FairValueInputsLevel1Member us-gaap:ForeignExchangeContractMember 2018-09-30 0000070145 us-gaap:FairValueInputsLevel2Member nfg:CommonStockFinancialServicesIndustryMember 2018-09-30 0000070145 us-gaap:FairValueInputsLevel2Member nfg:CommodityFuturesContractsGasMember 2018-09-30 0000070145 us-gaap:FairValueInputsLevel3Member us-gaap:FixedIncomeFundsMember 2018-09-30 0000070145 us-gaap:FairValueInputsLevel3Member nfg:OverCounterSwapsGasAndOilMember 2018-09-30 0000070145 us-gaap:FairValueInputsLevel1Member nfg:CommonStockFinancialServicesIndustryMember 2018-09-30 0000070145 nfg:CommodityFuturesContractsGasMember 2018-09-30 0000070145 us-gaap:FairValueConcentrationOfCreditRiskMasterNettingArrangementsMember us-gaap:ForeignExchangeContractMember 2018-09-30 0000070145 us-gaap:FairValueInputsLevel2Member nfg:OverCounterSwapsGasAndOilMember 2018-09-30 0000070145 us-gaap:FairValueInputsLevel1Member nfg:OverCounterSwapsGasAndOilMember 2018-09-30 0000070145 us-gaap:FairValueInputsLevel1Member 2018-09-30 0000070145 us-gaap:FairValueInputsLevel3Member nfg:CommonStockFinancialServicesIndustryMember 2018-09-30 0000070145 us-gaap:FairValueConcentrationOfCreditRiskMasterNettingArrangementsMember nfg:BalancedEquityMutualFundMember 2018-09-30 0000070145 us-gaap:FairValueConcentrationOfCreditRiskMasterNettingArrangementsMember 2018-09-30 0000070145 nfg:OverCounterSwapsGasAndOilMember 2018-09-30 0000070145 nfg:BalancedEquityMutualFundMember 2018-09-30 0000070145 us-gaap:FairValueInputsLevel2Member us-gaap:ForeignExchangeContractMember 2018-09-30 0000070145 us-gaap:FairValueInputsLevel2Member nfg:BalancedEquityMutualFundMember 2018-09-30 0000070145 us-gaap:FairValueConcentrationOfCreditRiskMasterNettingArrangementsMember nfg:OverCounterSwapsGasAndOilMember 2018-09-30 0000070145 us-gaap:FairValueInputsLevel1Member nfg:CommodityFuturesContractsGasMember 2018-09-30 0000070145 us-gaap:FairValueInputsLevel2Member us-gaap:FixedIncomeFundsMember 2018-09-30 0000070145 us-gaap:FairValueInputsLevel3Member us-gaap:ForeignExchangeContractMember 2018-09-30 0000070145 nfg:CommonStockFinancialServicesIndustryMember 2018-09-30 0000070145 us-gaap:FairValueInputsLevel3Member 2018-09-30 0000070145 us-gaap:FairValueConcentrationOfCreditRiskMasterNettingArrangementsMember nfg:CommodityFuturesContractsGasMember 2018-09-30 0000070145 us-gaap:FixedIncomeFundsMember 2018-09-30 0000070145 us-gaap:FairValueInputsLevel2Member 2018-09-30 0000070145 us-gaap:FairValueInputsLevel1Member us-gaap:FixedIncomeFundsMember 2018-09-30 0000070145 us-gaap:FairValueConcentrationOfCreditRiskMasterNettingArrangementsMember us-gaap:FixedIncomeFundsMember 2018-09-30 0000070145 us-gaap:FairValueInputsLevel3Member nfg:CommodityFuturesContractsGasMember 2018-09-30 0000070145 us-gaap:ForeignExchangeContractMember 2018-09-30 0000070145 us-gaap:FairValueInputsLevel3Member nfg:BalancedEquityMutualFundMember 2018-09-30 0000070145 us-gaap:FairValueConcentrationOfCreditRiskMasterNettingArrangementsMember nfg:CommonStockFinancialServicesIndustryMember 2018-09-30 0000070145 us-gaap:FairValueInputsLevel1Member nfg:BalancedEquityMutualFundMember 2018-09-30 0000070145 us-gaap:FutureMember us-gaap:FairValueInputsLevel1Member 2018-09-30 0000070145 nfg:DerivativeFinancialInstrumentsMember 2019-09-30 0000070145 us-gaap:FutureMember us-gaap:FairValueInputsLevel1Member 2019-09-30 0000070145 us-gaap:FairValueInputsLevel1Member 2019-09-30 0000070145 us-gaap:ForeignExchangeContractMember 2019-09-30 0000070145 us-gaap:FairValueInputsLevel3Member nfg:CommodityFuturesContractsGasMember 2019-09-30 0000070145 nfg:OverCounterSwapsGasAndOilMember 2019-09-30 0000070145 us-gaap:FairValueInputsLevel2Member us-gaap:ForeignExchangeContractMember 2019-09-30 0000070145 us-gaap:FairValueConcentrationOfCreditRiskMasterNettingArrangementsMember nfg:CommodityFuturesContractsGasMember 2019-09-30 0000070145 nfg:BalancedEquityMutualFundMember 2019-09-30 0000070145 us-gaap:FairValueInputsLevel2Member 2019-09-30 0000070145 us-gaap:FairValueInputsLevel1Member us-gaap:FixedIncomeFundsMember 2019-09-30 0000070145 us-gaap:FixedIncomeFundsMember 2019-09-30 0000070145 us-gaap:FairValueInputsLevel3Member us-gaap:ForeignExchangeContractMember 2019-09-30 0000070145 us-gaap:FairValueInputsLevel3Member nfg:OverCounterSwapsGasAndOilMember 2019-09-30 0000070145 us-gaap:FairValueConcentrationOfCreditRiskMasterNettingArrangementsMember nfg:CommonStockFinancialServicesIndustryMember 2019-09-30 0000070145 us-gaap:FairValueConcentrationOfCreditRiskMasterNettingArrangementsMember 2019-09-30 0000070145 us-gaap:FairValueConcentrationOfCreditRiskMasterNettingArrangementsMember us-gaap:FixedIncomeFundsMember 2019-09-30 0000070145 us-gaap:FairValueInputsLevel2Member nfg:CommodityFuturesContractsGasMember 2019-09-30 0000070145 nfg:CommodityFuturesContractsGasMember 2019-09-30 0000070145 us-gaap:FairValueInputsLevel1Member nfg:CommonStockFinancialServicesIndustryMember 2019-09-30 0000070145 us-gaap:FairValueInputsLevel2Member nfg:OverCounterSwapsGasAndOilMember 2019-09-30 0000070145 us-gaap:FairValueInputsLevel3Member nfg:CommonStockFinancialServicesIndustryMember 2019-09-30 0000070145 us-gaap:FairValueInputsLevel1Member nfg:OverCounterSwapsGasAndOilMember 2019-09-30 0000070145 us-gaap:FairValueConcentrationOfCreditRiskMasterNettingArrangementsMember nfg:BalancedEquityMutualFundMember 2019-09-30 0000070145 us-gaap:FairValueInputsLevel1Member nfg:BalancedEquityMutualFundMember 2019-09-30 0000070145 us-gaap:FairValueInputsLevel3Member 2019-09-30 0000070145 us-gaap:FairValueInputsLevel2Member nfg:CommonStockFinancialServicesIndustryMember 2019-09-30 0000070145 us-gaap:FairValueConcentrationOfCreditRiskMasterNettingArrangementsMember us-gaap:ForeignExchangeContractMember 2019-09-30 0000070145 us-gaap:FairValueInputsLevel1Member us-gaap:ForeignExchangeContractMember 2019-09-30 0000070145 us-gaap:FairValueInputsLevel1Member nfg:CommodityFuturesContractsGasMember 2019-09-30 0000070145 us-gaap:FairValueInputsLevel3Member nfg:BalancedEquityMutualFundMember 2019-09-30 0000070145 us-gaap:FairValueInputsLevel2Member nfg:BalancedEquityMutualFundMember 2019-09-30 0000070145 us-gaap:FairValueConcentrationOfCreditRiskMasterNettingArrangementsMember nfg:OverCounterSwapsGasAndOilMember 2019-09-30 0000070145 us-gaap:FairValueInputsLevel2Member us-gaap:FixedIncomeFundsMember 2019-09-30 0000070145 us-gaap:FairValueInputsLevel3Member us-gaap:FixedIncomeFundsMember 2019-09-30 0000070145 nfg:CommonStockFinancialServicesIndustryMember 2019-09-30 0000070145 nfg:DerivativeFinancialInstrumentsMember 2018-09-30 0000070145 nfg:EquityMutualFundMember 2018-09-30 0000070145 nfg:EquityMutualFundMember 2019-09-30 0000070145 us-gaap:EquitySecuritiesMember 2019-09-30 0000070145 us-gaap:EquitySecuritiesMember 2018-09-30 0000070145 us-gaap:CommodityContractMember 2018-10-01 2019-09-30 0000070145 nfg:OvertheCounterSwapsandForeignCurrencyForwardContractsMember 2019-09-30 0000070145 nfg:FixedPriceCommitmentsRelatedToWithdrawalOfStorageGasMmcfMember 2019-09-30 0000070145 nfg:OvertheCounterSwapsandForeignCurrencyForwardContractsMember nfg:CreditRiskRelatedContingencyFeatureMember 2019-09-30 0000070145 nfg:FixedPriceSalesCommitmentsMmcfMember 2019-09-30 0000070145 nfg:ExchangeTradedFuturesContractsMember 2019-09-30 0000070145 nfg:FairValueHedgesMmcfMember 2019-09-30 0000070145 nfg:OperatingRevenuesMember us-gaap:ForeignExchangeContractMember 2018-10-01 2019-09-30 0000070145 nfg:OperatingRevenuesMember us-gaap:ForeignExchangeContractMember 2017-10-01 2018-09-30 0000070145 us-gaap:CommodityContractMember nfg:OperatingRevenuesMember 2018-10-01 2019-09-30 0000070145 us-gaap:CommodityContractMember nfg:PurchasedGasMember 2018-10-01 2019-09-30 0000070145 us-gaap:CommodityContractMember nfg:OperatingRevenuesMember 2017-10-01 2018-09-30 0000070145 us-gaap:CommodityContractMember nfg:PurchasedGasMember 2017-10-01 2018-09-30 0000070145 nfg:OperatingRevenuesMember 2018-10-01 2019-09-30 0000070145 nfg:PurchasedGasMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasMmcfMember nfg:CashFlowHedgesShortPositionMember 2019-09-30 0000070145 nfg:CrudeOilBblsMember nfg:CashFlowHedgesShortPositionMember 2019-09-30 0000070145 nfg:NaturalGasMmcfMember nfg:CashFlowHedgesLongPositionMember 2019-09-30 0000070145 us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:RetirementSavingsAccountMember 2018-10-01 2019-09-30 0000070145 nfg:CurrentMember us-gaap:NonqualifiedPlanMember 2017-09-30 0000070145 us-gaap:NonqualifiedPlanMember 2018-09-30 0000070145 nfg:DiscountRateChangeMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2016-10-01 2017-09-30 0000070145 us-gaap:NonqualifiedPlanMember 2017-09-30 0000070145 nfg:RetirementSavingsAccountMember 2017-10-01 2018-09-30 0000070145 nfg:DiscountRateChangeMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2017-10-01 2018-09-30 0000070145 nfg:ActuarialExperienceMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-10-01 2019-09-30 0000070145 nfg:EffectiveNextFiscalYearMember us-gaap:PensionPlansDefinedBenefitMember 2018-10-01 2019-09-30 0000070145 nfg:ActuarialExperienceMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2016-10-01 2017-09-30 0000070145 nfg:DiscountRateChangeMember us-gaap:PensionPlansDefinedBenefitMember 2018-10-01 2019-09-30 0000070145 us-gaap:NonqualifiedPlanMember 2019-09-30 0000070145 nfg:TaxDeferredSavingsPlansMember 2016-10-01 2017-09-30 0000070145 nfg:MortalityImprovementProjectionScaleMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2016-10-01 2017-09-30 0000070145 nfg:NonCurrentMember us-gaap:NonqualifiedPlanMember 2017-09-30 0000070145 nfg:DiscountRateChangeMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-10-01 2019-09-30 0000070145 nfg:MortalityImprovementProjectionScaleMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-10-01 2019-09-30 0000070145 nfg:NonQualifiedBenefitPlansOtherPostRetirementBenefitPlanAndRetirementPlanMember 2018-10-01 2019-09-30 0000070145 nfg:DiscountRateChangeMember us-gaap:PensionPlansDefinedBenefitMember 2016-10-01 2017-09-30 0000070145 srt:MinimumMember nfg:OtherSecuritiesMember nfg:RetirementPlanandVebaTrustsAnd401HAccountsMember 2019-09-30 0000070145 nfg:DiscountRateChangeMember us-gaap:PensionPlansDefinedBenefitMember 2017-10-01 2018-09-30 0000070145 nfg:ActuarialExperienceMember us-gaap:PensionPlansDefinedBenefitMember 2018-10-01 2019-09-30 0000070145 nfg:RetirementSavingsAccountMember 2016-10-01 2017-09-30 0000070145 us-gaap:NonqualifiedPlanMember 2017-10-01 2018-09-30 0000070145 srt:MaximumMember us-gaap:EquitySecuritiesMember nfg:RetirementPlanandVebaTrustsAnd401HAccountsMember 2019-09-30 0000070145 nfg:TaxDeferredSavingsPlansMember 2017-10-01 2018-09-30 0000070145 nfg:VebaTrustsMember 2018-10-01 2019-09-30 0000070145 nfg:NonCurrentMember us-gaap:NonqualifiedPlanMember 2019-09-30 0000070145 nfg:ActuarialExperienceMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2017-10-01 2018-09-30 0000070145 nfg:MortalityImprovementProjectionScaleMember us-gaap:PensionPlansDefinedBenefitMember 2018-10-01 2019-09-30 0000070145 nfg:TaxDeferredSavingsPlansMember 2018-10-01 2019-09-30 0000070145 srt:MinimumMember us-gaap:FixedIncomeFundsMember nfg:RetirementPlanandVebaTrustsAnd401HAccountsMember 2019-09-30 0000070145 srt:MaximumMember us-gaap:FixedIncomeFundsMember nfg:RetirementPlanandVebaTrustsAnd401HAccountsMember 2019-09-30 0000070145 nfg:EffectiveNextFiscalYearMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-10-01 2019-09-30 0000070145 nfg:MortalityImprovementProjectionScaleMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2017-10-01 2018-09-30 0000070145 srt:MaximumMember nfg:OtherSecuritiesMember nfg:RetirementPlanandVebaTrustsAnd401HAccountsMember 2019-09-30 0000070145 nfg:OtherThanVebaTrustAnd401Member 2018-10-01 2019-09-30 0000070145 srt:MaximumMember us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 srt:MinimumMember us-gaap:EquitySecuritiesMember nfg:RetirementPlanandVebaTrustsAnd401HAccountsMember 2019-09-30 0000070145 srt:MinimumMember nfg:VebaTrustsMember 2019-09-30 0000070145 srt:MaximumMember nfg:VebaTrustsMember 2019-09-30 0000070145 nfg:NonCurrentMember us-gaap:NonqualifiedPlanMember 2018-09-30 0000070145 us-gaap:NonqualifiedPlanMember 2016-10-01 2017-09-30 0000070145 srt:MinimumMember us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 us-gaap:NonqualifiedPlanMember 2018-10-01 2019-09-30 0000070145 us-gaap:DefinedBenefitPlanRealEstateMember us-gaap:PensionPlansDefinedBenefitMember 2018-10-01 2019-09-30 0000070145 us-gaap:PensionPlansDefinedBenefitMember 2017-09-30 0000070145 us-gaap:DefinedBenefitPlanRealEstateMember us-gaap:PensionPlansDefinedBenefitMember 2017-10-01 2018-09-30 0000070145 us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:ExcludingFourHundredAndOneHInvestmentsMember us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 us-gaap:PensionPlansDefinedBenefitMember 2017-10-01 2018-09-30 0000070145 nfg:ExcludingFourHundredAndOneHInvestmentsMember us-gaap:PensionPlansDefinedBenefitMember 2017-10-01 2018-09-30 0000070145 nfg:ExcludingFourHundredAndOneHInvestmentsMember us-gaap:PensionPlansDefinedBenefitMember 2018-10-01 2019-09-30 0000070145 us-gaap:DefinedBenefitPlanRealEstateMember us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 us-gaap:DefinedBenefitPlanRealEstateMember us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:ExcludingFourHundredAndOneHInvestmentsMember us-gaap:PensionPlansDefinedBenefitMember 2017-09-30 0000070145 us-gaap:DefinedBenefitPlanRealEstateMember us-gaap:PensionPlansDefinedBenefitMember 2017-09-30 0000070145 nfg:ExcludingFourHundredAndOneHInvestmentsMember us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:FourHundredAndOneHInvestmentsMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2017-10-01 2018-09-30 0000070145 nfg:FourHundredAndOneHInvestmentsMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:FourHundredAndOneHInvestmentsMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2017-09-30 0000070145 nfg:FourHundredAndOneHInvestmentsMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:FourHundredAndOneHInvestmentsMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-10-01 2019-09-30 0000070145 us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2016-10-01 2017-09-30 0000070145 us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2017-10-01 2018-09-30 0000070145 us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2017-09-30 0000070145 us-gaap:PensionPlansDefinedBenefitMember 2016-10-01 2017-09-30 0000070145 us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 us-gaap:PensionPlansDefinedBenefitMember 2016-09-30 0000070145 us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2016-09-30 0000070145 nfg:TotalInvestmentsIncluding401hInvestmentsMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:TotalInvestmentsIncluding401hInvestmentsMember us-gaap:FairValueInputsLevel2Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:TotalInvestmentsIncluding401hInvestmentsMember us-gaap:FairValueInputsLevel1Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:CollectiveTrustFundsGlobalEquitiesMember us-gaap:FairValueInputsLevel1Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:CollectiveTrustFundsGlobalEquitiesMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:MiscellaneousAccrualsIncludingCurrentandDeferredTaxesClaimsIncurredButNotReportedAdministrativeMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:CollectiveTrustFundsGlobalEquitiesMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:CashHeldInCollectiveTrustFundsMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:FourHundredAndOneHInvestmentsMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:CashHeldInCollectiveTrustFundsMember us-gaap:FairValueInputsLevel2Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 us-gaap:ExchangeTradedFundsMember us-gaap:FairValueInputsLevel1Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:TotalInvestmentsIncluding401hInvestmentsMember us-gaap:FairValueInputsLevel3Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:CashHeldInCollectiveTrustFundsMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:FourHundredAndOneHInvestmentsMember us-gaap:FairValueInputsLevel1Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:FourHundredAndOneHInvestmentsMember us-gaap:FairValueInputsLevel2Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 us-gaap:ExchangeTradedFundsMember us-gaap:FairValueInputsLevel3Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:CollectiveTrustFundsGlobalEquitiesMember us-gaap:FairValueInputsLevel3Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:CashHeldInCollectiveTrustFundsMember us-gaap:FairValueInputsLevel3Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:TotalVebaTrustInvestmentsMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:TotalVebaTrustInvestmentsMember us-gaap:FairValueInputsLevel3Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:CashHeldInCollectiveTrustFundsMember us-gaap:FairValueInputsLevel1Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 us-gaap:ExchangeTradedFundsMember us-gaap:FairValueInputsLevel2Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 us-gaap:ExchangeTradedFundsMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:TotalVebaTrustInvestmentsMember us-gaap:FairValueInputsLevel2Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:TotalVebaTrustInvestmentsMember us-gaap:FairValueInputsLevel1Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:TotalInvestmentsIncluding401hInvestmentsMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:FourHundredAndOneHInvestmentsMember us-gaap:FairValueInputsLevel3Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:CollectiveTrustFundsGlobalEquitiesMember us-gaap:FairValueInputsLevel2Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:TotalVebaTrustInvestmentsMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 us-gaap:ExchangeTradedFundsMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2019-09-30 0000070145 us-gaap:DefinedBenefitPlanRealEstateMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:InternationalEquitiesMember us-gaap:FairValueInputsLevel3Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:InternationalEquitiesMember us-gaap:FairValueInputsLevel1Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:FourHundredAndOneHInvestmentsMember us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:DomesticEquitiesMember us-gaap:FairValueInputsLevel3Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 us-gaap:DefinedBenefitPlanRealEstateMember us-gaap:FairValueInputsLevel3Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:CashHeldInCollectiveTrustFundsMember us-gaap:FairValueInputsLevel2Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:RetirementPlanInvestmentMember us-gaap:FairValueInputsLevel3Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:DomesticFixedIncomeMember us-gaap:FairValueInputsLevel1Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:InternationalEquitiesMember us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:RetirementPlanInvestmentMember us-gaap:FairValueInputsLevel1Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:InternationalFixedIncomeMember us-gaap:FairValueInputsLevel1Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:FourHundredAndOneHInvestmentsMember us-gaap:FairValueInputsLevel1Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:FourHundredAndOneHInvestmentsMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:InternationalEquitiesMember us-gaap:FairValueInputsLevel2Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:DomesticFixedIncomeMember us-gaap:FairValueInputsLevel3Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:DomesticFixedIncomeMember us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:FourHundredAndOneHInvestmentsMember us-gaap:FairValueInputsLevel3Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:GlobalEquitiesMember us-gaap:FairValueInputsLevel3Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:RetirementPlanInvestmentMember us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:CashHeldInCollectiveTrustFundsMember us-gaap:FairValueInputsLevel3Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:DomesticEquitiesMember us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:MiscellaneousAccrualsInterestReceivablesAndNonInterestCashMember us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:GlobalEquitiesMember us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:TotalRetirementPlanInvestmentsExcluding401HInvestmentsMember us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 us-gaap:DefinedBenefitPlanRealEstateMember us-gaap:FairValueInputsLevel1Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:GlobalEquitiesMember us-gaap:FairValueInputsLevel1Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:InternationalEquitiesMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:GlobalFixedIncomeMember us-gaap:FairValueInputsLevel2Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:DomesticEquitiesMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:GlobalFixedIncomeMember us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:CashHeldInCollectiveTrustFundsMember us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:RetirementPlanInvestmentMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:InternationalFixedIncomeMember us-gaap:FairValueInputsLevel2Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:DomesticEquitiesMember us-gaap:FairValueInputsLevel1Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:TotalRetirementPlanInvestmentsExcluding401HInvestmentsMember us-gaap:FairValueInputsLevel1Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:TotalRetirementPlanInvestmentsExcluding401HInvestmentsMember us-gaap:FairValueInputsLevel3Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:InternationalFixedIncomeMember us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:GlobalFixedIncomeMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 us-gaap:DefinedBenefitPlanRealEstateMember us-gaap:FairValueInputsLevel2Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:TotalRetirementPlanInvestmentsExcluding401HInvestmentsMember us-gaap:FairValueInputsLevel2Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:GlobalFixedIncomeMember us-gaap:FairValueInputsLevel1Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:GlobalEquitiesMember us-gaap:FairValueInputsLevel2Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:TotalRetirementPlanInvestmentsExcluding401HInvestmentsMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:CashHeldInCollectiveTrustFundsMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:DomesticEquitiesMember us-gaap:FairValueInputsLevel2Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:RetirementPlanInvestmentMember us-gaap:FairValueInputsLevel2Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:CashHeldInCollectiveTrustFundsMember us-gaap:FairValueInputsLevel1Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:DomesticFixedIncomeMember us-gaap:FairValueInputsLevel2Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:InternationalFixedIncomeMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:DomesticFixedIncomeMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:GlobalFixedIncomeMember us-gaap:FairValueInputsLevel3Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:InternationalFixedIncomeMember us-gaap:FairValueInputsLevel3Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:FourHundredAndOneHInvestmentsMember us-gaap:FairValueInputsLevel2Member us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:GlobalEquitiesMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:PensionPlansDefinedBenefitMember 2019-09-30 0000070145 nfg:CollectiveTrustFundsDomesticEquitiesMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:FourHundredAndOneHInvestmentsMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 us-gaap:ExchangeTradedFundsMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:TotalInvestmentsIncluding401hInvestmentsMember us-gaap:FairValueInputsLevel1Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:CollectiveTrustFundsInternationalEquitiesMember us-gaap:FairValueInputsLevel3Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:TotalVebaTrustInvestmentsMember us-gaap:FairValueInputsLevel1Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:CashHeldInCollectiveTrustFundsMember us-gaap:FairValueInputsLevel2Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:CashHeldInCollectiveTrustFundsMember us-gaap:FairValueInputsLevel3Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:TotalInvestmentsIncluding401hInvestmentsMember us-gaap:FairValueInputsLevel3Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:TotalVebaTrustInvestmentsMember us-gaap:FairValueInputsLevel3Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:CollectiveTrustFundsInternationalEquitiesMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:CollectiveTrustFundsDomesticEquitiesMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:FourHundredAndOneHInvestmentsMember us-gaap:FairValueInputsLevel1Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:CollectiveTrustFundsDomesticEquitiesMember us-gaap:FairValueInputsLevel2Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:CashHeldInCollectiveTrustFundsMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 us-gaap:ExchangeTradedFundsMember us-gaap:FairValueInputsLevel2Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:CollectiveTrustFundsInternationalEquitiesMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:TotalVebaTrustInvestmentsMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:TotalInvestmentsIncluding401hInvestmentsMember us-gaap:FairValueInputsLevel2Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:MiscellaneousAccrualsIncludingCurrentandDeferredTaxesClaimsIncurredButNotReportedAdministrativeMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:TotalInvestmentsIncluding401hInvestmentsMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 us-gaap:ExchangeTradedFundsMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:CollectiveTrustFundsInternationalEquitiesMember us-gaap:FairValueInputsLevel1Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:CollectiveTrustFundsDomesticEquitiesMember us-gaap:FairValueInputsLevel3Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:CashHeldInCollectiveTrustFundsMember us-gaap:FairValueInputsLevel1Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:TotalInvestmentsIncluding401hInvestmentsMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:FourHundredAndOneHInvestmentsMember us-gaap:FairValueInputsLevel2Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 us-gaap:ExchangeTradedFundsMember us-gaap:FairValueInputsLevel1Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:CollectiveTrustFundsInternationalEquitiesMember us-gaap:FairValueInputsLevel2Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:CashHeldInCollectiveTrustFundsMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:CollectiveTrustFundsDomesticEquitiesMember us-gaap:FairValueInputsLevel1Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:TotalVebaTrustInvestmentsMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:FourHundredAndOneHInvestmentsMember us-gaap:FairValueInputsLevel3Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:TotalVebaTrustInvestmentsMember us-gaap:FairValueInputsLevel2Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 us-gaap:ExchangeTradedFundsMember us-gaap:FairValueInputsLevel3Member us-gaap:OtherPostretirementBenefitPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:TotalRetirementPlanInvestmentsExcluding401HInvestmentsMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 us-gaap:DefinedBenefitPlanRealEstateMember us-gaap:FairValueInputsLevel3Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:CashHeldInCollectiveTrustFundsMember us-gaap:FairValueInputsLevel2Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:RetirementPlanInvestmentMember us-gaap:FairValueInputsLevel2Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:GlobalEquitiesMember us-gaap:FairValueInputsLevel2Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:CashHeldInCollectiveTrustFundsMember us-gaap:FairValueInputsLevel3Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:DomesticFixedIncomeMember us-gaap:FairValueInputsLevel3Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:TotalRetirementPlanInvestmentsExcluding401HInvestmentsMember us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:GlobalFixedIncomeMember us-gaap:FairValueInputsLevel1Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:DomesticEquitiesMember us-gaap:FairValueInputsLevel1Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:InternationalEquitiesMember us-gaap:FairValueInputsLevel2Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:FourHundredAndOneHInvestmentsMember us-gaap:FairValueInputsLevel2Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:FourHundredAndOneHInvestmentsMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:GlobalFixedIncomeMember us-gaap:FairValueInputsLevel3Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:DomesticEquitiesMember us-gaap:FairValueInputsLevel2Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:DomesticFixedIncomeMember us-gaap:FairValueInputsLevel1Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:DomesticEquitiesMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:RetirementPlanInvestmentMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:FourHundredAndOneHInvestmentsMember us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:DomesticEquitiesMember us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:InternationalFixedIncomeMember us-gaap:FairValueInputsLevel2Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:DomesticFixedIncomeMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:InternationalFixedIncomeMember us-gaap:FairValueInputsLevel3Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:RetirementPlanInvestmentMember us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:MiscellaneousAccrualsInterestReceivablesAndNonInterestCashMember us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:CashHeldInCollectiveTrustFundsMember us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:CashHeldInCollectiveTrustFundsMember us-gaap:FairValueInputsLevel1Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:TotalRetirementPlanInvestmentsExcluding401HInvestmentsMember us-gaap:FairValueInputsLevel2Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:RetirementPlanInvestmentMember us-gaap:FairValueInputsLevel1Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 us-gaap:DefinedBenefitPlanRealEstateMember us-gaap:FairValueInputsLevel2Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:GlobalFixedIncomeMember us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 us-gaap:DefinedBenefitPlanRealEstateMember us-gaap:FairValueInputsLevel1Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:CashHeldInCollectiveTrustFundsMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:TotalRetirementPlanInvestmentsExcluding401HInvestmentsMember us-gaap:FairValueInputsLevel1Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:InternationalFixedIncomeMember us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:InternationalFixedIncomeMember us-gaap:FairValueInputsLevel1Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:GlobalEquitiesMember us-gaap:FairValueInputsLevel1Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:GlobalFixedIncomeMember us-gaap:FairValueInputsLevel2Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:GlobalEquitiesMember us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:RetirementPlanInvestmentMember us-gaap:FairValueInputsLevel3Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:InternationalEquitiesMember us-gaap:FairValueInputsLevel3Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 us-gaap:DefinedBenefitPlanRealEstateMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:DomesticFixedIncomeMember us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:InternationalEquitiesMember us-gaap:FairValueInputsLevel1Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:InternationalFixedIncomeMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:InternationalEquitiesMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:DomesticEquitiesMember us-gaap:FairValueInputsLevel3Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:TotalRetirementPlanInvestmentsExcluding401HInvestmentsMember us-gaap:FairValueInputsLevel3Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:GlobalEquitiesMember us-gaap:FairValueInputsLevel3Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:FourHundredAndOneHInvestmentsMember us-gaap:FairValueInputsLevel1Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:DomesticFixedIncomeMember us-gaap:FairValueInputsLevel2Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:GlobalEquitiesMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:InternationalEquitiesMember us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:FourHundredAndOneHInvestmentsMember us-gaap:FairValueInputsLevel3Member us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:GlobalFixedIncomeMember us-gaap:FairValueMeasuredAtNetAssetValuePerShareMember us-gaap:PensionPlansDefinedBenefitMember 2018-09-30 0000070145 nfg:FormerManufacturedGasPlantSiteNewYorkMember 2019-09-30 0000070145 nfg:PipelineAndStorageGatheringAndUtilitySegmentsMember 2019-09-30 0000070145 us-gaap:EnvironmentalRestorationCostsMember 2018-10-01 2019-09-30 0000070145 nfg:TotalReportableSegmentsMember 2016-10-01 2017-09-30 0000070145 nfg:CorporateAndIntersegmentEliminationsMember 2017-09-30 0000070145 us-gaap:OperatingSegmentsMember nfg:TotalReportableSegmentsMember 2016-10-01 2017-09-30 0000070145 nfg:CorporateAndIntersegmentEliminationsMember 2016-10-01 2017-09-30 0000070145 us-gaap:IntersegmentEliminationMember nfg:ExplorationAndProductionMember 2016-10-01 2017-09-30 0000070145 us-gaap:IntersegmentEliminationMember nfg:AllOtherMember 2016-10-01 2017-09-30 0000070145 nfg:AllOtherMember 2016-10-01 2017-09-30 0000070145 us-gaap:OperatingSegmentsMember nfg:GatheringMember 2016-10-01 2017-09-30 0000070145 us-gaap:IntersegmentEliminationMember nfg:TotalReportableSegmentsMember 2016-10-01 2017-09-30 0000070145 us-gaap:IntersegmentEliminationMember nfg:PipelineAndStorageMember 2016-10-01 2017-09-30 0000070145 us-gaap:OperatingSegmentsMember nfg:PipelineAndStorageMember 2016-10-01 2017-09-30 0000070145 us-gaap:OperatingSegmentsMember nfg:CorporateAndIntersegmentEliminationsMember 2016-10-01 2017-09-30 0000070145 nfg:ExplorationAndProductionMember 2017-09-30 0000070145 us-gaap:IntersegmentEliminationMember nfg:UtilityMember 2016-10-01 2017-09-30 0000070145 nfg:PipelineAndStorageMember 2017-09-30 0000070145 us-gaap:OperatingSegmentsMember nfg:ExplorationAndProductionMember 2016-10-01 2017-09-30 0000070145 nfg:GatheringMember 2017-09-30 0000070145 us-gaap:OperatingSegmentsMember 2016-10-01 2017-09-30 0000070145 us-gaap:IntersegmentEliminationMember 2016-10-01 2017-09-30 0000070145 us-gaap:OperatingSegmentsMember nfg:UtilityMember 2016-10-01 2017-09-30 0000070145 us-gaap:IntersegmentEliminationMember nfg:GatheringMember 2016-10-01 2017-09-30 0000070145 us-gaap:OperatingSegmentsMember nfg:AllOtherMember 2016-10-01 2017-09-30 0000070145 nfg:AllOtherMember 2017-09-30 0000070145 nfg:UtilityMember 2017-09-30 0000070145 us-gaap:IntersegmentEliminationMember nfg:CorporateAndIntersegmentEliminationsMember 2016-10-01 2017-09-30 0000070145 nfg:TotalReportableSegmentsMember 2017-09-30 0000070145 us-gaap:OperatingSegmentsMember nfg:CorporateAndIntersegmentEliminationsMember 2018-10-01 2019-09-30 0000070145 us-gaap:IntersegmentEliminationMember nfg:AllOtherMember 2018-10-01 2019-09-30 0000070145 nfg:AllOtherMember 2019-09-30 0000070145 us-gaap:OperatingSegmentsMember nfg:AllOtherMember 2018-10-01 2019-09-30 0000070145 us-gaap:IntersegmentEliminationMember nfg:TotalReportableSegmentsMember 2018-10-01 2019-09-30 0000070145 us-gaap:OperatingSegmentsMember nfg:UtilityMember 2018-10-01 2019-09-30 0000070145 us-gaap:OperatingSegmentsMember 2018-10-01 2019-09-30 0000070145 us-gaap:IntersegmentEliminationMember nfg:UtilityMember 2018-10-01 2019-09-30 0000070145 nfg:CorporateAndIntersegmentEliminationsMember 2019-09-30 0000070145 us-gaap:IntersegmentEliminationMember nfg:CorporateAndIntersegmentEliminationsMember 2018-10-01 2019-09-30 0000070145 us-gaap:IntersegmentEliminationMember 2018-10-01 2019-09-30 0000070145 us-gaap:OperatingSegmentsMember nfg:PipelineAndStorageMember 2018-10-01 2019-09-30 0000070145 us-gaap:OperatingSegmentsMember nfg:GatheringMember 2018-10-01 2019-09-30 0000070145 us-gaap:IntersegmentEliminationMember nfg:PipelineAndStorageMember 2018-10-01 2019-09-30 0000070145 us-gaap:IntersegmentEliminationMember nfg:ExplorationAndProductionMember 2018-10-01 2019-09-30 0000070145 us-gaap:IntersegmentEliminationMember nfg:GatheringMember 2018-10-01 2019-09-30 0000070145 nfg:TotalReportableSegmentsMember 2019-09-30 0000070145 us-gaap:OperatingSegmentsMember nfg:ExplorationAndProductionMember 2018-10-01 2019-09-30 0000070145 us-gaap:OperatingSegmentsMember nfg:TotalReportableSegmentsMember 2018-10-01 2019-09-30 0000070145 country:US 2018-09-30 0000070145 country:US 2017-09-30 0000070145 country:US 2019-09-30 0000070145 us-gaap:OperatingSegmentsMember nfg:ExplorationAndProductionMember 2017-10-01 2018-09-30 0000070145 nfg:CorporateAndIntersegmentEliminationsMember 2017-10-01 2018-09-30 0000070145 nfg:TotalReportableSegmentsMember 2017-10-01 2018-09-30 0000070145 us-gaap:OperatingSegmentsMember nfg:GatheringMember 2017-10-01 2018-09-30 0000070145 nfg:CorporateAndIntersegmentEliminationsMember 2018-09-30 0000070145 nfg:AllOtherMember 2017-10-01 2018-09-30 0000070145 us-gaap:OperatingSegmentsMember nfg:CorporateAndIntersegmentEliminationsMember 2017-10-01 2018-09-30 0000070145 us-gaap:IntersegmentEliminationMember nfg:TotalReportableSegmentsMember 2017-10-01 2018-09-30 0000070145 us-gaap:IntersegmentEliminationMember nfg:ExplorationAndProductionMember 2017-10-01 2018-09-30 0000070145 us-gaap:OperatingSegmentsMember nfg:TotalReportableSegmentsMember 2017-10-01 2018-09-30 0000070145 us-gaap:IntersegmentEliminationMember 2017-10-01 2018-09-30 0000070145 us-gaap:OperatingSegmentsMember 2017-10-01 2018-09-30 0000070145 nfg:AllOtherMember 2018-09-30 0000070145 us-gaap:IntersegmentEliminationMember nfg:AllOtherMember 2017-10-01 2018-09-30 0000070145 us-gaap:IntersegmentEliminationMember nfg:PipelineAndStorageMember 2017-10-01 2018-09-30 0000070145 us-gaap:OperatingSegmentsMember nfg:PipelineAndStorageMember 2017-10-01 2018-09-30 0000070145 us-gaap:IntersegmentEliminationMember nfg:CorporateAndIntersegmentEliminationsMember 2017-10-01 2018-09-30 0000070145 us-gaap:IntersegmentEliminationMember nfg:GatheringMember 2017-10-01 2018-09-30 0000070145 us-gaap:OperatingSegmentsMember nfg:UtilityMember 2017-10-01 2018-09-30 0000070145 nfg:TotalReportableSegmentsMember 2018-09-30 0000070145 us-gaap:IntersegmentEliminationMember nfg:UtilityMember 2017-10-01 2018-09-30 0000070145 us-gaap:OperatingSegmentsMember nfg:AllOtherMember 2017-10-01 2018-09-30 0000070145 2018-01-01 2018-03-31 0000070145 2018-07-01 2018-09-30 0000070145 2017-10-01 2017-12-31 0000070145 2018-10-01 2018-12-31 0000070145 2019-01-01 2019-03-31 0000070145 2019-04-01 2019-06-30 0000070145 2018-04-01 2018-06-30 0000070145 srt:CrudeOilAndNGLPerBarrelMember nfg:WestCoastRegionMember 2018-10-01 2019-09-30 0000070145 srt:CrudeOilAndNGLPerBarrelMember nfg:AppalachianRegionMember 2017-10-01 2018-09-30 0000070145 srt:CrudeOilAndNGLPerBarrelMember 2017-10-01 2018-09-30 0000070145 srt:CrudeOilAndNGLPerBarrelMember nfg:AppalachianRegionMember 2018-10-01 2019-09-30 0000070145 srt:CrudeOilAndNGLPerBarrelMember 2017-09-30 0000070145 srt:CrudeOilAndNGLPerBarrelMember nfg:AppalachianRegionMember 2019-09-30 0000070145 srt:CrudeOilAndNGLPerBarrelMember nfg:WestCoastRegionMember 2019-09-30 0000070145 srt:CrudeOilAndNGLPerBarrelMember 2016-09-30 0000070145 srt:CrudeOilAndNGLPerBarrelMember 2016-10-01 2017-09-30 0000070145 srt:CrudeOilAndNGLPerBarrelMember nfg:WestCoastRegionMember 2018-09-30 0000070145 srt:CrudeOilAndNGLPerBarrelMember nfg:WestCoastRegionMember 2016-10-01 2017-09-30 0000070145 srt:CrudeOilAndNGLPerBarrelMember nfg:WestCoastRegionMember 2017-10-01 2018-09-30 0000070145 srt:CrudeOilAndNGLPerBarrelMember nfg:WestCoastRegionMember 2017-09-30 0000070145 srt:CrudeOilAndNGLPerBarrelMember 2018-09-30 0000070145 srt:CrudeOilAndNGLPerBarrelMember 2019-09-30 0000070145 srt:CrudeOilAndNGLPerBarrelMember nfg:AppalachianRegionMember 2016-10-01 2017-09-30 0000070145 srt:CrudeOilAndNGLPerBarrelMember nfg:AppalachianRegionMember 2017-09-30 0000070145 srt:CrudeOilAndNGLPerBarrelMember nfg:AppalachianRegionMember 2016-09-30 0000070145 srt:CrudeOilAndNGLPerBarrelMember nfg:AppalachianRegionMember 2018-09-30 0000070145 srt:CrudeOilAndNGLPerBarrelMember 2018-10-01 2019-09-30 0000070145 srt:CrudeOilAndNGLPerBarrelMember nfg:WestCoastRegionMember 2016-09-30 0000070145 nfg:CapitalizedCostsOfUnprovedPropertiesCumulativeBalanceMember 2018-10-01 2019-09-30 0000070145 nfg:CostsIncurredPriorYearsMember 2015-10-01 2016-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember nfg:AppalachianRegionMember 2016-10-01 2017-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember 2017-10-01 2018-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember nfg:WestCoastRegionMember 2019-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember nfg:AppalachianRegionMember 2018-10-01 2019-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember 2016-10-01 2017-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember nfg:WestCoastRegionMember 2016-10-01 2017-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember 2017-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember nfg:WestCoastRegionMember 2018-10-01 2019-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember nfg:WestCoastRegionMember 2017-10-01 2018-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember nfg:AppalachianRegionMember 2019-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember 2019-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember nfg:WestCoastRegionMember 2018-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember nfg:AppalachianRegionMember 2018-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember nfg:AppalachianRegionMember 2017-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember nfg:AppalachianRegionMember 2017-10-01 2018-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember nfg:WestCoastRegionMember 2017-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember 2018-10-01 2019-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember 2018-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember nfg:AppalachianRegionMember 2016-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember 2016-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember nfg:WestCoastRegionMember 2016-09-30 0000070145 nfg:OilCondensateAndOtherLiquidsMember 2016-10-01 2017-09-30 0000070145 nfg:NaturalGasMember 2017-10-01 2018-09-30 0000070145 nfg:OilCondensateAndOtherLiquidsMember 2018-10-01 2019-09-30 0000070145 nfg:NaturalGasMember 2016-10-01 2017-09-30 0000070145 nfg:OilCondensateAndOtherLiquidsMember 2017-10-01 2018-09-30 0000070145 nfg:NaturalGasMember 2018-10-01 2019-09-30 0000070145 nfg:UticaShaleMember 2018-10-01 2019-09-30 0000070145 nfg:WestCoastRegionMember 2018-09-30 0000070145 nfg:MarcellusShaleFieldsMember 2019-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember nfg:UticaShaleMember 2018-10-01 2019-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember nfg:MarcellusShaleFieldsMember 2017-10-01 2018-09-30 0000070145 nfg:UticaShaleMember 2018-09-30 0000070145 nfg:UticaShaleMember 2017-09-30 0000070145 nfg:ImpactofJDASalesMember 2018-09-30 0000070145 2015-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember nfg:MarcellusShaleFieldsMember 2018-10-01 2019-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember nfg:MarcellusShaleFieldsMember 2016-10-01 2017-09-30 0000070145 nfg:MarcellusShaleFieldsMember 2018-10-01 2019-09-30 0000070145 nfg:MarcellusShaleFieldsMember 2017-09-30 0000070145 nfg:UticaShaleMember 2019-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember nfg:UticaShaleMember 2017-10-01 2018-09-30 0000070145 nfg:MarcellusShaleFieldsMember 2018-09-30 0000070145 nfg:WestCoastRegionMember 2019-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember nfg:UticaShaleMember 2016-10-01 2017-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember nfg:UticaShaleMember 2019-09-30 0000070145 nfg:TotalPudReserveAdditionsEstimatedInTheNextFiscalYearMember 2018-10-01 2019-09-30 0000070145 srt:NaturalGasPerThousandCubicFeetMember nfg:MarcellusShaleFieldsMember 2019-09-30 0000070145 us-gaap:AllowanceForCreditLossMember 2017-10-01 2018-09-30 0000070145 us-gaap:ValuationAllowanceOfDeferredTaxAssetsMember 2017-10-01 2018-09-30 0000070145 us-gaap:AllowanceForCreditLossMember 2016-09-30 0000070145 us-gaap:AllowanceForCreditLossMember 2017-09-30 0000070145 us-gaap:AllowanceForCreditLossMember 2018-09-30 0000070145 us-gaap:AllowanceForCreditLossMember 2018-10-01 2019-09-30 0000070145 us-gaap:AllowanceForCreditLossMember 2019-09-30 0000070145 us-gaap:AllowanceForCreditLossMember 2016-10-01 2017-09-30 0000070145 us-gaap:ValuationAllowanceOfDeferredTaxAssetsMember 2017-09-30 0000070145 us-gaap:ValuationAllowanceOfDeferredTaxAssetsMember 2019-09-30 0000070145 us-gaap:ValuationAllowanceOfDeferredTaxAssetsMember 2018-09-30 0000070145 us-gaap:ValuationAllowanceOfDeferredTaxAssetsMember 2018-10-01 2019-09-30 iso4217:USD xbrli:shares xbrli:shares iso4217:USD xbrli:pure utreg:MMcf nfg:counterparty utreg:bbl utreg:MBbls nfg:segment utreg:ft3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 10-K

For the Fiscal Year Ended September 30, 2019

(716) 857-7000

(Registrant’s telephone number, including area code)

Securities registered pursuant to Section 12(g) of the Act: None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.    Yes  ☑        No  ☐

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15 (d) of the Act.    Yes  ☐        No  ☑

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 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 such filing requirements for the past 90 days.    Yes  ☑        No  ☐

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 such files).    Yes  ☑        No  ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, 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 is a shell company (as defined in Rule 12b-2 of the Act).    Yes  ☐        No  ☑

The aggregate market value of the voting stock held by nonaffiliates of the registrant amounted to $5,152,011,000 as of March 31, 2019.

Common Stock, par value $1.00 per share, outstanding as of October 31, 2019: 86,324,767 shares.

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the registrant’s definitive Proxy Statement for its 2020 Annual Meeting of Stockholders, to be filed with the Securities and Exchange Commission within 120 days of September 30, 2019, are incorporated by reference into Part III of this report.

For the Fiscal Year Ended September 30, 2019