SWX


Line plots across dimensions of each concept
Line plots across concepts
Tables

Table of contents



us-gaap:CommonStockValue
dei:LegalEntity, us-gaap:StatementEquityComponents
us-gaap:CommonStockSharesOutstanding
us-gaap:StatementEquityComponents

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic

us-gaap:EarningsPerShareBasic

us-gaap:EarningsPerShareDiluted

us-gaap:ComprehensiveIncomeNetOfTax

us-gaap:ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest
dei:LegalEntity

us-gaap:CostOfGoodsAndServicesSold

us-gaap:CostsAndExpenses
dei:LegalEntity

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
dei:LegalEntity

us-gaap:IncomeTaxExpenseBenefit
dei:LegalEntity

us-gaap:IncomeTaxesPaidNet
dei:LegalEntity

us-gaap:InterestExpense
dei:LegalEntity

us-gaap:InterestPaidNet
dei:LegalEntity

us-gaap:NetIncomeLoss
dei:LegalEntity
us-gaap:ConsolidationItems
us-gaap:StatementBusinessSegments

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest

us-gaap:NonoperatingIncomeExpense
dei:LegalEntity

us-gaap:OperatingIncomeLoss
dei:LegalEntity

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax
dei:LegalEntity

us-gaap:OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax

us-gaap:OtherComprehensiveIncomeLossNetOfTax
dei:LegalEntity
dei:LegalEntity, us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents

us-gaap:OtherNonoperatingIncomeExpense
dei:LegalEntity
dei:LegalEntity, us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments
us-gaap:ConsolidationItems

us-gaap:ProfitLoss
dei:LegalEntity

us-gaap:RegulatedAndUnregulatedOperatingRevenue
dei:LegalEntity

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax
dei:LegalEntity
dei:LegalEntity, us-gaap:ContractWithCustomerBasisOfPricing
dei:LegalEntity, us-gaap:ProductOrService
us-gaap:MajorCustomers

us-gaap:Revenues
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments
us-gaap:StatementBusinessSegments

us-gaap:Assets
dei:LegalEntity
us-gaap:ConsolidationItems
us-gaap:StatementBusinessSegments

us-gaap:LiabilitiesAndStockholdersEquity
dei:LegalEntity

us-gaap:StockholdersEquity
dei:LegalEntity
dei:LegalEntity, us-gaap:StatementEquityComponents

us-gaap:AssetsCurrent
dei:LegalEntity

us-gaap:CashAndCashEquivalentsAtCarryingValue
dei:LegalEntity

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents
dei:LegalEntity

us-gaap:AccountsReceivableNetCurrent
dei:LegalEntity

us-gaap:PrepaidExpenseAndOtherAssetsCurrent
dei:LegalEntity
dei:LegalEntity
us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment

us-gaap:Goodwill
us-gaap:StatementBusinessSegments
dei:LegalEntity
us-gaap:FiniteLivedIntangibleAssetsNet
dei:LegalEntity, us-gaap:FiniteLivedIntangibleAssetsByMajorClass
dei:LegalEntity
us-gaap:OperatingLeaseRightOfUseAsset

us-gaap:OtherAssetsNoncurrent
dei:LegalEntity

us-gaap:AccountsPayableCurrent
dei:LegalEntity

us-gaap:AccruedIncomeTaxesCurrent
dei:LegalEntity

us-gaap:ContractWithCustomerLiabilityCurrent
dei:LegalEntity

us-gaap:DividendsPayableCurrent
dei:LegalEntity

us-gaap:LiabilitiesCurrent
dei:LegalEntity

us-gaap:LongTermDebtCurrent
dei:LegalEntity
dei:LegalEntity, us-gaap:FairValueByMeasurementBasis
dei:LegalEntity, us-gaap:LongtermDebtType
us-gaap:FairValueByMeasurementBasis
dei:LegalEntity
us-gaap:OperatingLeaseLiabilityCurrent

us-gaap:OtherLiabilitiesCurrent
dei:LegalEntity
dei:LegalEntity, us-gaap:CreditFacility
us-gaap:LongTermDebt
dei:LegalEntity, us-gaap:FairValueByMeasurementBasis
dei:LegalEntity, us-gaap:LongtermDebtType

us-gaap:LongTermDebtNoncurrent
dei:LegalEntity
dei:LegalEntity, us-gaap:FairValueByMeasurementBasis
us-gaap:FairValueByMeasurementBasis

us-gaap:OtherLiabilitiesNoncurrent
dei:LegalEntity
dei:LegalEntity
us-gaap:OperatingLeaseLiabilityNoncurrent
dei:LegalEntity
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo
dei:LegalEntity
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree
dei:LegalEntity
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour
dei:LegalEntity
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive
dei:LegalEntity
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive
dei:LegalEntity
us-gaap:OperatingLeaseLiability
dei:LegalEntity
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue
dei:LegalEntity
us-gaap:LesseeOperatingLeaseLiabilityUndiscountedExcessAmount

us-gaap:StockholdersEquity
dei:LegalEntity
dei:LegalEntity, us-gaap:StatementEquityComponents

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
dei:LegalEntity
dei:LegalEntity, us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents

us-gaap:CommonStockValue

us-gaap:AdditionalPaidInCapitalCommonStock
dei:LegalEntity

us-gaap:RetainedEarningsAccumulatedDeficit
dei:LegalEntity

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax
dei:LegalEntity
us-gaap:PlanName
us-gaap:StockIssuedDuringPeriodValueNewIssues
us-gaap:StatementEquityComponents

us-gaap:NetCashProvidedByUsedInOperatingActivities
dei:LegalEntity

us-gaap:NetCashProvidedByUsedInInvestingActivities
dei:LegalEntity

us-gaap:NetCashProvidedByUsedInFinancingActivities
dei:LegalEntity

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect
dei:LegalEntity

us-gaap:IncreaseDecreaseInAccountsPayable
dei:LegalEntity

us-gaap:IncreaseDecreaseInAccountsReceivable
dei:LegalEntity

us-gaap:NetCashProvidedByUsedInOperatingActivities
dei:LegalEntity

us-gaap:NetIncomeLoss
dei:LegalEntity
us-gaap:ConsolidationItems
us-gaap:StatementBusinessSegments

us-gaap:ProfitLoss
dei:LegalEntity

us-gaap:ShareBasedCompensation
dei:LegalEntity

us-gaap:NetCashProvidedByUsedInInvestingActivities
dei:LegalEntity

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment
dei:LegalEntity

us-gaap:NetCashProvidedByUsedInFinancingActivities
dei:LegalEntity

us-gaap:ProceedsFromIssuanceOfLongTermDebt
dei:LegalEntity

us-gaap:RepaymentsOfLongTermDebt
dei:LegalEntity

us-gaap:PaymentsOfDividendsCommonStock
dei:LegalEntity

us-gaap:EffectiveIncomeTaxRateContinuingOperations

us-gaap:DeferredTaxLiabilities
dei:LegalEntity

us-gaap:DeferredTaxAssetsNet
dei:LegalEntity

us-gaap:UnrecognizedTaxBenefits
dei:LegalEntity

us-gaap:DeferredTaxAssetsValuationAllowance
dei:LegalEntity

us-gaap:ProceedsFromRepaymentsOfShortTermDebt
dei:LegalEntity
dei:LegalEntity, us-gaap:StatementEquityComponents
swx:AdjustmentsToAdditionalPaidInCapitalContributionsFromParent

swx:AlternativeRevenueProgramRevenuesDeferrals

swx:AmountsBilledInExcessOfRevenueEarnedOnContracts

swx:ChangesInCustomerAdvancesInvestingActivities
dei:LegalEntity
us-gaap:SubsidiarySaleOfStock
swx:CommonStockWeightedAverageIssuePricePerShare

swx:DeferredPurchasedGasCostsEstimatedIncrementalCosts
us-gaap:Range, us-gaap:SubsequentEventType

swx:DeferredPurchasedGasCostsPipelineImbalanceCharges

swx:IncreaseDecreaseInAccruedTaxes
dei:LegalEntity
dei:LegalEntity, us-gaap:LongtermDebtType
swx:LineOfCreditFacilityMinimumAmountOutstandingDuringPeriod
dei:LegalEntity, us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments
swx:MiscellaneousIncomeExpense

swx:NumberOfPerformanceShareUnitsGranted

swx:OtherComprehensiveIncomeDefinedBenefitPlansRegulatoryAdjustmentNetOfTax
dei:LegalEntity
dei:LegalEntity, us-gaap:StatementEquityComponents
swx:OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTaxOther
us-gaap:StatementEquityComponents

swx:OtherRevenue
us-gaap:SubsidiarySaleOfStock
swx:ProceedsFromIssuanceOfCommonStockGross

swx:ProceedsFromRepaymentsOfLinesOfCreditAndCommercialPaper
dei:LegalEntity

swx:RevenueEarnedOnContractsInProgressInExcessOfBillings
us-gaap:BusinessAcquisition
us-gaap:BusinessCombinationConsiderationTransferred1

us-gaap:ContractWithCustomerAssetReclassifiedToReceivable

us-gaap:ContractWithCustomerLiabilityRevenueRecognized
dei:LegalEntity, us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments
us-gaap:DefinedBenefitPlanActuarialGainLossImmediateRecognitionAsComponentInNetPeriodicBenefitCostCredit
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAmortizationOfGainsLosses
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAmortizationOfPriorServiceCostCredit
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanExpectedReturnOnPlanAssets
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanInterestCost
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanNetPeriodicBenefitCost
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanServiceCost

us-gaap:DepreciationAndAmortization
dei:LegalEntity
dei:LegalEntity, us-gaap:StatementEquityComponents
us-gaap:DividendsCommonStock
us-gaap:StatementEquityComponents

us-gaap:EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

us-gaap:FinanceLeasePrincipalPayments
dei:LegalEntity, us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments
us-gaap:ForeignCurrencyTransactionGainLossRealized

us-gaap:GainLossOnSaleOfPropertyPlantEquipment

us-gaap:GoodwillForeignCurrencyTranslationGainLoss
us-gaap:StatementBusinessSegments

us-gaap:IncreaseDecreaseInAccruedTaxesPayable
dei:LegalEntity

us-gaap:IncreaseDecreaseInAllowanceForEquityFundsUsedDuringConstruction
dei:LegalEntity

us-gaap:IncreaseDecreaseInContractWithCustomerAsset
dei:LegalEntity

us-gaap:IncreaseDecreaseInDeferredGasCost
dei:LegalEntity

us-gaap:IncreaseDecreaseInDeferredIncomeTaxes
dei:LegalEntity

us-gaap:IncreaseDecreaseInOtherCurrentAssetsAndLiabilitiesNet
dei:LegalEntity

us-gaap:IncreaseDecreaseInOtherOperatingAssets
dei:LegalEntity

us-gaap:IncreaseDecreaseInOtherOperatingLiabilities
dei:LegalEntity

us-gaap:IncrementalCommonSharesAttributableToNonvestedSharesWithForfeitableDividends
dei:LegalEntity, us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments
us-gaap:InterestIncomeOther
dei:LegalEntity, us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments
us-gaap:LifeInsuranceCorporateOrBankOwnedChangeInValue
dei:LegalEntity, us-gaap:LongtermDebtType
us-gaap:LineOfCreditFacilityMaximumAmountOutstandingDuringPeriod

us-gaap:MinorityInterestChangeInRedemptionValue
us-gaap:StatementEquityComponents

us-gaap:NetIncomeLossAttributableToRedeemableNoncontrollingInterest
dei:LegalEntity, us-gaap:StatementEquityComponents
us-gaap:NetIncomeLossIncludingPortionAttributableToNonredeemableNoncontrollingInterest
us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents
us-gaap:OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentBeforeTaxPortionAttributableToParent

us-gaap:OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax
dei:LegalEntity
us-gaap:StatementEquityComponents
us-gaap:OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax

us-gaap:OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax
us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeLossBeforeTax
dei:LegalEntity
dei:LegalEntity, us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax
dei:LegalEntity
dei:LegalEntity, us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax
dei:LegalEntity

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax
dei:LegalEntity

us-gaap:OtherComprehensiveIncomeLossTax
dei:LegalEntity
dei:LegalEntity, us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents

us-gaap:PaymentsForProceedsFromOtherInvestingActivities
dei:LegalEntity
us-gaap:SubsidiarySaleOfStock
us-gaap:PaymentsOfStockIssuanceCosts

us-gaap:PaymentsRelatedToTaxWithholdingForShareBasedCompensation
dei:LegalEntity

us-gaap:PaymentsToAcquireBusinessesNetOfCashAcquired
dei:LegalEntity
us-gaap:ProceedsFromContributionsFromParent

us-gaap:ProceedsFromIssuanceOfCommonStock
us-gaap:SubsidiarySaleOfStock

us-gaap:ProceedsFromPaymentsForOtherFinancingActivities
dei:LegalEntity
dei:LegalEntity, us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments
us-gaap:PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity
dei:LegalEntity, us-gaap:StatementEquityComponents
us-gaap:ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax
us-gaap:StatementEquityComponents
dei:LegalEntity, us-gaap:StatementEquityComponents
us-gaap:ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax
us-gaap:StatementEquityComponents
dei:LegalEntity, us-gaap:StatementEquityComponents
us-gaap:ReclassificationFromAociCurrentPeriodTax
us-gaap:StatementEquityComponents

us-gaap:RegulatedOperatingRevenueGas
dei:LegalEntity
us-gaap:PlanName
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod
us-gaap:StatementEquityComponents
us-gaap:StockIssuedDuringPeriodSharesNewIssues
dei:LegalEntity, us-gaap:StatementEquityComponents
us-gaap:StockIssuedDuringPeriodValueShareBasedCompensation

us-gaap:TaxesExcludingIncomeAndExciseTaxes
dei:LegalEntity

us-gaap:UtilitiesOperatingExpenseGasAndPetroleumPurchased
dei:LegalEntity

us-gaap:UtilitiesOperatingExpenseMaintenanceAndOperations
dei:LegalEntity

swx:AccruedPropertyTaxes

swx:AccruedUtilityRevenue
dei:LegalEntity

swx:BilledOnCompletedContractsAndContractsInProgress

swx:DebtInstrumentPercentageOfTotalWithInterestRatesReferenceToLIBORAndDueAfter2021
dei:LegalEntity
dei:LegalEntity, us-gaap:DebtInstrument, us-gaap:FairValueByMeasurementBasis
swx:DebtInstrumentUnamortizedDiscountAndDebtIssuanceCosts

swx:DeferredIncomeTaxesAndUnamortizedInvestmentTaxCredits
dei:LegalEntity

swx:DeferredTaxAssetsLeaseRelatedItem

swx:DeferredTaxLiabilitiesLeaseRelatedItem

swx:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeLossAmountRecognizedRegulatoryAssetsBeforeTax

swx:FutureEstimatedFundingAmountInNextFiscalYear
us-gaap:RetirementPlanType

swx:IncomeTaxesPayableNet
us-gaap:SubsidiarySaleOfStock
swx:MaximumAmountOfCommonStockAvailableForSale

swx:NetRegulatoryLiabilities
us-gaap:IncomeTaxAuthority
swx:OperatingLossCarryforwardsNetOfFederalBenefit

swx:OtherPropertyAndInvestments
dei:LegalEntity
dei:LegalEntity
swx:PropertyPlantEquipmentAndIntangibleAssetsGross

swx:PublicUtilitiesPropertyPlantAndEquipmentGasPlant
dei:LegalEntity

swx:PublicUtilitiesPropertyPlantandEquipmentGasPlant
dei:LegalEntity
us-gaap:FiniteLivedIntangibleAssetsByMajorClass
us-gaap:PublicUtility
us-gaap:SubsidiarySaleOfStock
swx:SaleOfStockCommonStockAvailableForSale
dei:LegalEntity, us-gaap:StatementEquityComponents
swx:StockholdersEquityAttributableToParentBeforeTax
dei:LegalEntity, us-gaap:StatementEquityComponents
swx:StockholdersEquityAttributableToParentTax
us-gaap:StatementEquityComponents
swx:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestBeforeTax
us-gaap:StatementEquityComponents
swx:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestTax

us-gaap:AccountsReceivableGross

us-gaap:AccountsReceivableNet

us-gaap:AccrualForTaxesOtherThanIncomeTaxesCurrent
dei:LegalEntity

us-gaap:AllowanceForDoubtfulAccountsReceivable

us-gaap:AssetsNoncurrentOtherThanNoncurrentInvestmentsAndPropertyPlantAndEquipment
dei:LegalEntity

us-gaap:CapitalizationLongtermDebtAndEquity
dei:LegalEntity
dei:LegalEntity, us-gaap:CashAndCashEquivalents
us-gaap:CashAndCashEquivalentsFairValueDisclosure
us-gaap:CashAndCashEquivalents
dei:LegalEntity
us-gaap:CashSurrenderValueOfLifeInsurance

us-gaap:CommonStockCapitalSharesReservedForFutureIssuance

us-gaap:ContractWithCustomerAssetAccumulatedAllowanceForCreditLoss

us-gaap:ContractWithCustomerAssetGross
us-gaap:AccountsNotesLoansAndFinancingReceivableByReceivableType

us-gaap:ContractWithCustomerAssetNet

us-gaap:ContractWithCustomerLiability
dei:LegalEntity, us-gaap:LongtermDebtType
us-gaap:DebtInstrumentCollateralAmount
dei:LegalEntity, us-gaap:DebtInstrument
us-gaap:DebtInstrumentInterestRateEffectivePercentage
dei:LegalEntity, us-gaap:LongtermDebtType
us-gaap:LongtermDebtType
dei:LegalEntity, us-gaap:CreditFacility
us-gaap:DebtWeightedAverageInterestRate
us-gaap:CreditFacility

us-gaap:DeferredCreditsAndOtherLiabilitiesNoncurrent
dei:LegalEntity

us-gaap:DeferredGasCost
dei:LegalEntity

us-gaap:DeferredGasPurchasesCurrent
dei:LegalEntity

us-gaap:DeferredIncomeTaxAssetsNet

us-gaap:DeferredIncomeTaxLiabilities
dei:LegalEntity

us-gaap:DeferredTaxAssetsOperatingLossCarryforwards

us-gaap:DeferredTaxAssetsOther
dei:LegalEntity

us-gaap:DeferredTaxAssetsTaxCreditCarryforwards
dei:LegalEntity

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits
dei:LegalEntity

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation
dei:LegalEntity

us-gaap:DeferredTaxLiabilitiesDeferredExpenseDeferredFinancingCosts
dei:LegalEntity

us-gaap:DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets

us-gaap:DeferredTaxLiabilitiesOther
dei:LegalEntity

us-gaap:DeferredTaxLiabilitiesPropertyPlantAndEquipment
dei:LegalEntity

us-gaap:DeferredTaxLiabilitiesRegulatoryAssetsAndLiabilities
dei:LegalEntity
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAccumulatedBenefitObligation

us-gaap:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax

us-gaap:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax

us-gaap:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanBenefitObligation
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo

us-gaap:DefinedBenefitPlanFairValueOfPlanAssets
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanFundedStatusOfPlan
us-gaap:Range, us-gaap:DefinedBenefitPlanByPlanAssetCategories
us-gaap:DefinedBenefitPlanPlanAssetsTargetAllocationPercentage
dei:LegalEntity
us-gaap:DueFromRelatedPartiesCurrent
dei:LegalEntity
us-gaap:DueToAffiliateCurrent

us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
dei:LegalEntity
us-gaap:FinanceLeaseLiability
dei:LegalEntity
us-gaap:FinanceLeaseLiabilityCurrent
dei:LegalEntity
us-gaap:FinanceLeaseLiabilityNoncurrent
dei:LegalEntity
us-gaap:FinanceLeaseLiabilityPaymentsDue
dei:LegalEntity
us-gaap:FinanceLeaseLiabilityPaymentsDueNextTwelveMonths
dei:LegalEntity
us-gaap:FinanceLeaseLiabilityPaymentsDueYearFour
dei:LegalEntity
us-gaap:FinanceLeaseLiabilityPaymentsDueYearThree
dei:LegalEntity
us-gaap:FinanceLeaseLiabilityPaymentsDueYearTwo
dei:LegalEntity
us-gaap:FinanceLeaseLiabilityUndiscountedExcessAmount
dei:LegalEntity
us-gaap:FinanceLeaseRightOfUseAsset
dei:LegalEntity
us-gaap:FinanceLeaseWeightedAverageDiscountRatePercent
dei:LegalEntity
us-gaap:FiniteLivedIntangibleAssetsAccumulatedAmortization
dei:LegalEntity, us-gaap:FiniteLivedIntangibleAssetsByMajorClass
dei:LegalEntity
us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive
dei:LegalEntity
us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths
dei:LegalEntity
us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearFive
dei:LegalEntity
us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearFour
dei:LegalEntity
us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearThree
dei:LegalEntity
us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo
dei:LegalEntity
us-gaap:FiniteLivedIntangibleAssetsGross
dei:LegalEntity, us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:IncomeTaxesReceivable
dei:LegalEntity

us-gaap:InterestPayableCurrent
dei:LegalEntity

us-gaap:InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet
dei:LegalEntity
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths
dei:LegalEntity, us-gaap:DebtInstrument, us-gaap:FairValueByMeasurementBasis, us-gaap:LongtermDebtType
us-gaap:LineOfCredit
dei:LegalEntity, us-gaap:LongtermDebtType
dei:LegalEntity, us-gaap:VariableRate
us-gaap:CreditFacility
dei:LegalEntity, us-gaap:DebtInstrument, us-gaap:FairValueByMeasurementBasis, us-gaap:LongtermDebtType
us-gaap:LinesOfCreditFairValueDisclosure

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths
dei:LegalEntity

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive
dei:LegalEntity

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour
dei:LegalEntity

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree
dei:LegalEntity

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo
dei:LegalEntity
us-gaap:BalanceSheetLocation, us-gaap:PublicUtilitiesInventory
us-gaap:MaterialsSuppliesAndOther
dei:LegalEntity, us-gaap:DebtInstrument, us-gaap:FairValueByMeasurementBasis
us-gaap:NotesPayable
dei:LegalEntity, us-gaap:DebtInstrument, us-gaap:FairValueByMeasurementBasis, us-gaap:LongtermDebtType
dei:LegalEntity, us-gaap:DebtInstrument, us-gaap:FairValueByMeasurementBasis, us-gaap:LongtermDebtType
us-gaap:NotesPayableFairValueDisclosure
dei:LegalEntity
us-gaap:OperatingLeaseWeightedAverageDiscountRatePercent
us-gaap:IncomeTaxAuthority
us-gaap:OperatingLossCarryforwards

us-gaap:OtherAccruedLiabilitiesNoncurrent
dei:LegalEntity
dei:LegalEntity, us-gaap:FairValueByMeasurementBasis, us-gaap:LongtermDebtType
us-gaap:OtherLongTermDebt

us-gaap:OtherReceivables

us-gaap:PropertyPlantAndEquipmentOtherNet
dei:LegalEntity

us-gaap:PublicUtilitiesPropertyPlantAndEquipmentAccumulatedDepreciation
dei:LegalEntity

us-gaap:PublicUtilitiesPropertyPlantAndEquipmentConstructionWorkInProgress
dei:LegalEntity

us-gaap:PublicUtilitiesPropertyPlantAndEquipmentNet
dei:LegalEntity

us-gaap:RedeemableNoncontrollingInterestEquityCarryingAmount

us-gaap:RegulatoryAssets
us-gaap:BalanceSheetLocation, us-gaap:RegulatoryAsset
us-gaap:RegulatoryAsset
us-gaap:BalanceSheetLocation, us-gaap:PublicUtilitiesInventory
us-gaap:RegulatoryAssetsCurrent
us-gaap:BalanceSheetLocation
us-gaap:RegulatoryLiabilities
us-gaap:RegulatoryLiability
dei:LegalEntity
us-gaap:RevenueRemainingPerformanceObligation
dei:LegalEntity, us-gaap:CreditFacility, us-gaap:FairValueByMeasurementBasis
us-gaap:SecuredDebt
dei:LegalEntity, us-gaap:FairValueByMeasurementBasis
dei:LegalEntity, us-gaap:FairValueByMeasurementBasis, us-gaap:LongtermDebtType
us-gaap:PlanName
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
us-gaap:PlanName
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue

us-gaap:ShortTermBorrowings
dei:LegalEntity
dei:LegalEntity, us-gaap:CreditFacility
us-gaap:CreditFacility
dei:LegalEntity
us-gaap:ShortTermLeaseCommitmentAmount
us-gaap:TaxCreditCarryforward
us-gaap:TaxCreditCarryforwardAmount
dei:LegalEntity, us-gaap:FairValueByMeasurementBasis
us-gaap:UnamortizedDebtIssuanceExpense

us-gaap:UndistributedEarningsOfForeignSubsidiaries

us-gaap:UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate
dei:LegalEntity
dei:LegalEntity, us-gaap:DebtInstrument, us-gaap:FairValueByMeasurementBasis
us-gaap:UnsecuredDebt
dei:LegalEntity, us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
us-gaap:VariableInterestEntityEntityMaximumLossExposureAmount

Plots across concepts


IncomeStatement
Other Comprehensive Income Loss Net Of Tax
Expenses
Other Nonoperating Income Expense
Balance Sheet
Cash And Cash Equivalents At Carrying Value
Assets
Cash And Cash Equivalents At Carrying Value
Current Assets
Cash And Cash Equivalents At Carrying Value
NonCurrent Assets
Deferred Income Tax Assets Net
Liabilities
Liabilities Current
Current Liabilities
Accrued Income Taxes Current
Noncurrent Liabilities
Other Liabilities Noncurrent
Stockholders Equity
Accumulated Other Comprehensive Income Loss Net Of Tax
CashFlow
Net Cash Provided By Used In Investing Activities
NetCashProvidedByUsedInOperatingActivities
Increase Decrease In Accounts Payable
NetCashProvidedByUsedInInvestingActivities
Net Cash Provided By Used In Investing Activities
NetCashProvidedByUsedInFinancingActivities
Proceeds From Payments For Other Financing Activities
Shares
Weighted Average Number Of Shares Outstanding Basic
NonoperatingIncomeExpense
Nonoperating Income Expense

Tables

  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
us-gaap:CommonStockValue █▇▇▆▆▆▆▅▅▅▄▂▂▂▁▁▁▁▁60.71859.62558.82358.08957.5456.75656.63756.25455.95155.02154.65651.05350.75649.96749.7249.36249.21349.17949.112NANANA49.007NANANANANANANA
 us-gaap:CommonStockSharesOutstanding dei:LegalEntity,us-gaap:StatementEquityComponents swx:SouthwestGasCorporation,us-gaap:CommonStock▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄47.48247.48247.48247.48247.48247.48247.48247.48247.48247.48247.48247.48247.48247.48247.48247.48247.48247.48247.482NANANA47.377NANANANANANANA
 us-gaap:CommonStockSharesOutstanding us-gaap:StatementEquityComponents us-gaap:CommonStock█▇▇▆▆▆▆▅▅▅▄▂▂▂▁▁▁▁▁59.08857.99557.19356.45955.9155.12655.00754.62454.32153.39153.02649.42349.12648.33748.0947.73247.58347.54947.482NANANA47.377NANANA46.523NANANA
us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding █▁58.7157.679NA56.35755.53255.363NA54.74854.00353.424NA49.55348.8848.459NA47.98647.88447.864NA47.8347.81147.763NANANANANANANANA
us-gaap:WeightedAverageNumberOfSharesOutstandingBasic █▁58.60757.6NA56.27155.46255.31NA54.6753.93553.369NA49.49348.82648.416NA47.62847.57147.53NA47.48147.47347.437NANANANANANANANA
us-gaap:EarningsPerShareBasic ▃█▇▂▄▆▇▂▃▇▆▂▃▇█▂▃▆▆▁▂▇▆▁▂▆▅▁▂▆0.432.041.820.320.681.311.670.10.411.781.360.250.441.632.00.210.381.461.370.050.191.591.4-0.10.111.541.260.040.211.52
us-gaap:EarningsPerShareDiluted ▃█▇▂▄▆▇▂▃▇▆▂▃▇█▂▃▆▆▁▂▇▆▁▂▆▅▁▂▆0.432.031.820.320.681.311.670.10.411.771.360.250.441.632.00.210.371.451.360.050.191.581.38-0.10.11.531.250.040.211.51
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
 Cost Ratio dei:LegalEntity swx:SouthwestGasCorporationNANA374.49210.834262.434502.827379.571209.98258.711520.677370.213217.523275.679494.313366.485213.059260.162462.602641.525539.969547.748731.248NANANANANANANANA
 EBT Margin dei:LegalEntity swx:SouthwestGasCorporationNANA374.49210.834262.434502.827379.571209.98258.711520.677370.213217.523275.679494.313366.485213.059260.162462.602641.525539.969547.748731.248NANANANANANANANA
 Net profit Margin dei:LegalEntity swx:SouthwestGasCorporationNANA374.49210.834262.434502.827379.571209.98258.711520.677370.213217.523275.679494.313366.485213.059260.162462.602641.525539.969547.748731.248NANANANANANANANA
 Operating Margin dei:LegalEntity swx:SouthwestGasCorporationNANA374.49210.834262.434502.827379.571209.98258.711520.677370.213217.523275.679494.313366.485213.059260.162462.602641.525539.969547.748731.248685.405505.396538.604734.22NANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
us-gaap:ComprehensiveIncomeNetOfTax ▂█▇▂▃▅▆▁▂▇▅▂▂▆▆▂▂▅▅▁▁▅27.819119.90895.32421.10741.42170.20182.7616.15924.09896.85470.02614.46122.39479.7191.60112.34819.58470.63463.4723.36710.13477.328NANANANANANANANA
us-gaap:ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest ▅▆▅█▆▃▃▅▄▄▃▃▃▁▂▃▃▂▄▃▃▂1.3551.5521.4922.791.9160.4630.1881.1720.7760.5750.1720.00.0-0.797-0.0690.1980.279-0.2960.4980.4270.159-0.065NANANANANANANANA
us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest ▃█▇▂▃▅▆▁▂▇▅▂▂▅▆▂▂▅▅▁▁▅29.174121.4696.81623.89743.33770.66482.9497.33124.87497.42970.19814.46122.39478.91391.53212.54619.86370.33863.973.79410.29377.263NANANANANANANANA
us-gaap:CostOfGoodsAndServicesSold ▇▃▇█▆▃▆▇▅▂▄▅▄▁▃▃▁478.64335.614476.94502.951430.224319.314418.989451.574402.199300.465380.204395.862352.671258.952342.377342.629272.001NANANANANANANANANANANANANA
us-gaap:CostsAndExpenses █▇█▇▆▆▇▆▅▆▅▄▄▄▄▂▁▂▁▁▁▃762.155712.454761.285736.962689.675687.947709.933686.972658.142693.059651.8628.465617.545624.77609.765563.021517.061535.245523.562524.43519.632597.152NANANANANANANANA
us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest ▂█▇▂▃▆▆▁▂▇▆▂▂▆▆▂▂▆▆▁▂▇32.016149.937128.71627.75249.04799.223112.8989.66629.184120.92297.73916.02226.98102.595114.07313.51426.8104.643101.116-0.05412.365118.096NANANANANANANANA
us-gaap:IncomeTaxExpenseBenefit ▂▆▅▂▃▅▅▂▂▅▆▂▂▅▄▂▃▇▇▁▂█5.54231.09223.686.6899.16626.21820.9923.1416.35225.53828.2633.6915.42924.30117.6773.0948.67935.63835.422-2.9613.26642.741NANANANANANANANA
us-gaap:IncomeTaxesPaidNet ▇▆▇▆▆▂▆▅▆▆▃▆█▇▆▆▆▆▁▆▆▆5.0081.6515.0553.4040.654-20.0642.381-1.4611.3780.454-17.041.75412.0894.4181.9860.6441.2161.827-25.5621.7932.6012.136NANANANANANANANA
us-gaap:InterestExpense ▆▅██▇██▇▇▇▆▅▅▄▃▂▂▂▂▁▁▁25.93923.96428.33628.31126.4528.3828.56427.43426.83126.39725.8424.54823.65222.63121.20119.49418.65518.71419.5618.15818.22117.721NANANANANANANANA
us-gaap:InterestPaidNet █▁█▂▇▂█▂▆▃▇▁▅▂▅▁▅▁▄▂▄▁39.1728.30341.43912.31338.35713.07340.09312.16934.14615.8536.9949.48626.78813.29426.17210.58924.89410.28820.30613.9122.63110.593NANANANANANANANA
us-gaap:NetIncomeLoss ▃█▇▂▃▅▇▂▃▇▅▂▃▆▇▂▂▅▅▁▂▆▅▁▂▅▅▁▂▅25.119117.293103.54418.27337.96572.54291.7185.35322.05694.80969.30412.33121.55179.09196.46510.20417.86469.30865.182.4728.94375.44666.119-4.7344.94971.98358.7461.979.62770.783
us-gaap:NetIncomeLossAttributableToNoncontrollingInterest ▅▆▅█▆▃▃▅▄▄▃▃▃▁▂▃▃▂▄▃▃▂1.3551.5521.4922.791.9160.4630.1881.1720.7760.5750.1720.00.0-0.797-0.0690.2160.257-0.3030.5140.4350.156-0.091NANANANANANANANA
us-gaap:NonoperatingIncomeExpense ▅▆▆▆▇▁▆▅▆▇▃▆▆▆████████-27.25-23.516-24.079-26.512-18.525-49.15-25.306-28.592-25.685-19.558-37.115-23.659-26.358-26.965-16.595-16.618-16.608-14.849-16.847-15.593-15.751-16.0NANANANANANANANA
 us-gaap:NonoperatingIncomeExpense dei:LegalEntity swx:SouthwestGasCorporation▅▆▆▆▇▁▆▆▆▇▄▇▆▆████▇███-25.34-21.616-21.639-24.352-16.153-45.594-21.631-24.972-21.753-17.153-33.316-19.563-22.243-23.858-13.819-14.34-14.939-13.599-16.278-13.843-14.125-14.475NANANANANANANANA
us-gaap:OperatingIncomeLoss ▃█▇▃▃▇▆▂▃▇▆▂▃▆▆▂▂▆▆▁▂▆▆▁▁▆▅▁▁▆59.266173.453152.79554.26467.572148.373138.20438.25854.869140.48134.85439.68153.338129.56130.66830.13243.408119.492117.96315.53928.116134.096117.58616.14325.047129.556112.37318.2926.755127.065
us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax ▁▁▁█▅▅▅▅▅0.4140.4130.4130.7830.6350.6360.6350.6350.636NANANANANANANANANANANANANANANANANANANANANA
us-gaap:OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax ▆▆█▆▇▁▆▅▆▆▃▆▄▄▅▆▆▅▅▅▅▆0.9090.8232.91.0241.794-4.0050.907-0.4470.7870.791-2.0080.599-0.69-0.911-0.091.0120.6290.22-0.453-0.2380.070.782NANANANANANANANA
us-gaap:OtherComprehensiveIncomeLossNetOfTax ██▁██▅▁▇▇▇▆▇▇▆▃▇▇▇▅▇▇▇2.72.615-8.222.8343.456-2.341-8.9570.8062.0422.0450.7222.130.8430.619-4.8642.1261.7421.333-1.7240.8871.1941.908NANANANANANANANA
us-gaap:OtherNonoperatingIncomeExpense ▆▆▇▇█▁▇▆▆█▃▆▅▅▇▇▇▇▇▇▇▆-1.3110.4484.2571.7997.925-20.773.258-1.1581.1466.839-11.2750.889-2.706-4.3344.6062.8762.0473.8652.7132.5652.471.721NANANANANANANANA
 us-gaap:OtherNonoperatingIncomeExpense dei:LegalEntity swx:SouthwestGasCorporation▆▆▇▆█▁▇▆▆█▃▆▆▅▇▇▇▇▆▇▇▆-1.1650.554.3571.7517.838-20.5363.332-1.3531.5925.946-11.3790.836-2.094-4.6034.2923.0812.0523.6111.5642.5212.4361.755NANANANANANANANA
 us-gaap:OtherNonoperatingIncomeExpense dei:LegalEntity,us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments swx:CenturiGroupInc.,us-gaap:OperatingSegments,swx:UtilityInfrastructureServicesSegment▃▃▃▄▄▃▃▅▂█▄▄▁▅-0.146-0.102-0.10.0480.087-0.242-0.1030.171-0.4770.8750.0930.038-0.6320.263NANANANANANANANANANANANANANANANA
 us-gaap:OtherNonoperatingIncomeExpense dei:LegalEntity,us-gaap:ConsolidationItems,us-gaap:StatementBusinessSegments swx:SouthwestGasCorporation,us-gaap:OperatingSegments,swx:NaturalGasOperations▆▆▇▆█▁▇▆▆█▃▆▆▅▆▆-1.1650.554.3571.7517.838-20.5363.332-1.3531.5925.946-11.3790.836-2.094-4.603-0.564-1.775NANANANANANANANANANANANANANA
 us-gaap:OtherNonoperatingIncomeExpense us-gaap:ConsolidationItems us-gaap:CorporateNonSegmentNANA0.00.00.00.0080.0290.0240.0310.0180.0110.0150.020.0060.0070.005NANANANANANANANANANANANANANA
us-gaap:ProfitLoss ▃▇▇▂▃▅▆▂▂▆█▂▂▅▆▂▂▅▅▁▂▅▅▁▁▅▄▁▂▅26.474118.845105.03621.06339.88173.00591.9066.52522.83295.384131.1612.33121.55178.29496.39610.4218.12169.00565.6942.9079.09975.35566.698-4.215.06371.87958.8971.9279.62770.697
us-gaap:RegulatedAndUnregulatedOperatingRevenue ▇██▆▆▇▇▅▅▇▆▄▄▆▅▃▃▄▄▃▃▅▅▂▃▅▄▁▁▄821.421885.907914.08791.226757.247836.32848.137725.23713.011833.539786.654668.146670.883754.33740.433593.153560.469654.737641.525539.969547.748731.248685.405505.396538.604734.22627.683432.475453.153608.396
us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax ▂▄█▁▂▄▇▁▂▄▇▁▂▄▆▁▄▄▅▄▄▆▆▄▄▆▅▃▄▅291.344535.52914.08203.082259.066504.793848.137200.256253.408552.18786.654196.837261.699478.558740.433202.159537.546465.64641.525512.71521.991709.061685.405505.396538.604734.22627.683432.475453.153608.396
us-gaap:Revenues ▇██▆▆▇▇▅▅▇▆▄▄▅▅▃▃▄▄▂▂▅▅▂▃▅▄▁▁▄821.421885.907914.08791.226757.247836.32848.137725.23713.011833.539786.654668.146637.811727.172740.433564.909537.546633.441641.525512.71521.991709.061685.405505.396538.604734.22627.683432.475453.153608.396
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
us-gaap:Assets ██▇▇▇▆▆▆▅▅▅▃▃▃▂▂▁▁▁9039.0228928.6458735.8538429.6578426.0358093.2258170.0487840.2117666.8857569.4327357.7296654.5966476.3936327.6336237.0665855.075665.2395551.9135581.126NANANA5358.685NANANA5208.297NANANA
us-gaap:LiabilitiesAndStockholdersEquity ██▇▇▇▆▆▆▅▅▅▃▃▃▂▂▁▁▁9039.0228928.6458735.8538429.6578426.0358093.2258170.0487840.2117666.8857569.4327357.7296654.5966476.3936327.6336237.0665855.075665.2395551.9135581.126NANANA5358.685NANANANANANANA
us-gaap:StockholdersEquity ██▇▇▇▆▆▅▅▅▄▃▃▂▂▁▁▁▁2846.8812773.7222674.9532619.2382611.2952547.8952505.9142423.712419.3632347.02252.0421946.2331933.0191879.5381814.7681715.6911716.5681715.3811663.49NANANA1594.408NANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
us-gaap:AssetsCurrent ██▆▅▆▄▆▅▅▆▆▄▄▄▄▂▁▁▂1006.7951000.904871.013732.828867.2672.919859.856765.402752.081830.38839.769721.193696.059663.933657.032538.918483.585454.404533.307NANANA558.174NANANANANANANA
us-gaap:CashAndCashEquivalentsAtCarryingValue ▂▄▄▁█▃▂▂▂▄▄▃▂▃▂▃▂▂▂▄▁▃▂▂▂▂▂47.56592.34583.35223.945199.59160.96549.53928.4838.44697.03785.36169.1734.7365.11543.62259.15229.70243.40128.06685.15412.12660.80935.99732.95948.90938.01339.566NANANA
us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents ▂▄▄▁█▃▂▂▂▄▄▃▂▃▂▃▂▂▂▄▁47.56592.34583.35223.945199.59160.96549.53928.4838.44697.03785.36169.1734.7365.11543.62259.15229.70243.40128.06685.15412.126NA35.997NANANANANANANA
us-gaap:AccountsReceivableNetCurrent █▇██▇▅▇▆▅▆▅▄▄▃▄▂▂▁▂512.385479.184522.172513.017480.077423.013474.097434.153417.639429.248413.926347.571357.881335.982347.375301.792281.882247.179285.145NANANA314.512NANANANANANANA
us-gaap:PrepaidExpenseAndOtherAssetsCurrent ▃▂▄▃▃▂▅▅▅▅█▇█▅▄▂▂▁▃149.402133.466170.152151.432147.655133.338180.957190.554187.666177.784243.701220.249250.992181.248165.294132.182126.192104.27136.833NANANA95.199NANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
 us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment dei:LegalEntity swx:CenturiGroupInc.█▇▆▆▅▄▃▃▂▂▁457.698439.126422.741406.59384.108363.074352.333345.113332.683316.832298.939NANANANANANANANANANANANANANANANANANANA
us-gaap:Goodwill ▇▇▇▇▇▇▇▇▇██▂▂▂▂▁▁▁▁348.173346.553345.184340.197337.978333.943343.023339.948345.872364.482359.045176.059174.233176.485179.314147.865143.583140.974139.983NANANA126.145NANANANANANANA
 us-gaap:FiniteLivedIntangibleAssetsNet dei:LegalEntity swx:CenturiGroupInc.NANA140.184NANANA150.511NANANA159.821NANANANANANANANANANANANANANANANANANANA
 us-gaap:FiniteLivedIntangibleAssetsNet dei:LegalEntity,us-gaap:FiniteLivedIntangibleAssetsByMajorClass swx:CenturiGroupInc.,us-gaap:CustomerRelationshipsNANA125.52NANANA133.451NANANA140.817NANANANANANANANANANANANANANANANANANANA
 us-gaap:FiniteLivedIntangibleAssetsNet dei:LegalEntity,us-gaap:FiniteLivedIntangibleAssetsByMajorClass swx:CenturiGroupInc.,us-gaap:TrademarksAndTradeNamesNANA14.664NANANA16.599NANANA17.779NANANANANANANANANANANANANANANANANANANA
 us-gaap:OperatingLeaseRightOfUseAsset dei:LegalEntity swx:CenturiGroupInc.NANA81.01NANANA78.95471.37760.30157.267NANANANANANANANANANANANANANANANANANANANA
 us-gaap:OperatingLeaseRightOfUseAsset dei:LegalEntity swx:SouthwestGasCorporationNANA2.195NANANA1.4432.0082.0721.977NANANANANANANANANANANANANANANANANANANANA
us-gaap:OtherAssetsNoncurrent ▆▇█▆▆▇▇▂▃▃▃▂▂▃▄▁▁▂▂488.042497.187508.875475.037474.737489.419496.943429.716436.035441.166440.862419.829425.555438.682447.41411.655416.261426.6432.234NANANA469.322NANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
us-gaap:AccountsPayableCurrent ▄▄▇▄▄▄▇▄▅▇█▃▄▄▇▃▁▁▄182.304182.805231.301175.507189.373182.182238.921188.896196.915231.343248.993172.237188.156175.905228.315159.382135.738134.238184.669NANANA164.857NANANANANANANA
us-gaap:AccruedIncomeTaxesCurrent ██▆▁▁▁▂19.25919.35612.5561.0840.00.02.069NANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:ContractWithCustomerLiabilityCurrent ▁▇▇████44.08867.12167.9269.12269.89869.93869.165NANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:DividendsPayableCurrent █▆▁35.234.532.6NANANA30.0NANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LiabilitiesCurrent █▆▅▄▅▅▆▄▃▅▅▃▃▂▄▂▁▁▂1272.4031036.035911.967839.222918.017979.8151079.861782.344726.504974.478938.645712.71663.647602.851815.881656.406490.035496.828628.375NANANA535.045NANANANANANANA
us-gaap:LongTermDebtCurrent █▂▁▁▄▄▄▁▁▁▁▁▁▁▁▁▁▁▂319.41767.33440.43344.903171.668169.574163.51238.16536.80734.91533.0633.42931.92824.86725.34628.45327.23626.06450.101NANANA19.475NANANANANANANA
 us-gaap:OperatingLeaseLiabilityCurrent dei:LegalEntity swx:CenturiGroupInc.NANA10.032NANANA8.8518.1837.9657.178NANANANANANANANANANANANANANANANANANANANA
 us-gaap:OperatingLeaseLiabilityCurrent dei:LegalEntity swx:SouthwestGasCorporationNANA0.656NANANA0.7230.8260.8970.745NANANANANANANANANANANANANANANANANANANANA
us-gaap:OtherLiabilitiesCurrent █▆██▆▆▆▆▆▆▇▄▅▃▃▃▂▁▂317.97282.745328.945322.928289.395266.763264.95279.931269.674278.552290.878229.521262.113208.479203.403197.854175.043149.529168.064NANANA150.031NANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
 us-gaap:LongTermDebt dei:LegalEntity,us-gaap:CreditFacility swx:SouthwestGasCorporation,swx:A400MillionCreditFacilityNANANA58.00.0150.0NA150.0NANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LongTermDebt dei:LegalEntity,us-gaap:FairValueByMeasurementBasis swx:CenturiGroupInc.,us-gaap:CarryingReportedAmountFairValueDisclosure▄▁▂▇█▅▃▇█▁▁359.408325.316334.427384.749398.567363.034347.661384.411398.251322.23321.649NANANANANANANANANANANANANANANANANANANA
 us-gaap:LongTermDebt dei:LegalEntity,us-gaap:FairValueByMeasurementBasis swx:SouthwestGasCorporation,us-gaap:CarryingReportedAmountFairValueDisclosure███▇█▆▆▆▅▄▄▄▃▃▁▁▁2438.8322438.5882438.2062345.8762412.4182116.6242116.3332115.872011.5591818.9591818.6691818.6211716.3071706.9941521.0311520.791462.552NA1400.08NANANANANANANANANANANA
 us-gaap:LongTermDebt dei:LegalEntity,us-gaap:LongtermDebtType swx:SouthwestGasCorporation,swx:SouthwestGasCreditFacility▄▄▄150.0150.0150.0NANANA150.0NA46.0150.0150.0150.0NANANANANANANANANANANANANANANANANANA
us-gaap:LongTermDebtNoncurrent ▆███▇▆▅▆▆▄▄▄▄▄▂▂▂▁▁2478.8232696.572732.22685.7222639.3172310.0842300.4822462.1162373.0032106.2742107.2582123.6412037.7431998.1271798.5761731.9811685.6981564.1321549.983NANANA1551.204NANANANANANANA
us-gaap:OtherLiabilitiesNoncurrent ███▇▇▇▇▆▆▅▄▃▃▃▂▁▁▁▁2240.3862217.0322251.0172178.1912170.4852170.4262199.2492087.6872064.8332059.7261978.4051872.4641842.4361850.2791810.2061753.2871755.1011754.3091718.905NANANA1664.003NANANANANANANA
 us-gaap:OperatingLeaseLiabilityNoncurrent dei:LegalEntity swx:CenturiGroupInc.NANA75.247NANANA73.32365.79155.18552.647NANANANANANANANANANANANANANANANANANANANA
 us-gaap:OperatingLeaseLiabilityNoncurrent dei:LegalEntity swx:SouthwestGasCorporationNANA1.586NANANA0.731.2091.21.253NANANANANANANANANANANANANANANANANANANANA
 us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo dei:LegalEntity swx:CenturiGroupInc.NANA12.153NANANA11.23510.4169.5519.327NANANANANANANANANANANANANANANANANANANANA
 us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo dei:LegalEntity swx:SouthwestGasCorporationNANA0.543NANANA0.3760.5480.5340.556NANANANANANANANANANANANANANANANANANANANA
 us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree dei:LegalEntity swx:CenturiGroupInc.NANA10.864NANANA10.6139.6758.7368.328NANANANANANANANANANANANANANANANANANANANA
 us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree dei:LegalEntity swx:SouthwestGasCorporationNANA0.426NANANA0.1880.2440.2130.295NANANANANANANANANANANANANANANANANANANANA
 us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour dei:LegalEntity swx:CenturiGroupInc.NANA9.904NANANA8.8238.1927.5487.645NANANANANANANANANANANANANANANANANANANANA
 us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour dei:LegalEntity swx:SouthwestGasCorporationNANA0.404NANANA0.0780.0790.1020.124NANANANANANANANANANANANANANANANANANANANA
 us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive dei:LegalEntity swx:CenturiGroupInc.NANA8.051NANANA8.0656.9735.9925.71NANANANANANANANANANANANANANANANANANANANA
 us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive dei:LegalEntity swx:SouthwestGasCorporationNANA0.33NANANA0.0560.0790.0780.078NANANANANANANANANANANANANANANANANANANANA
 us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive dei:LegalEntity swx:CenturiGroupInc.NANA50.605NANANA49.86245.56434.23931.303NANANANANANANANANANANANANANANANANANANANA
 us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive dei:LegalEntity swx:SouthwestGasCorporationNANA0.036NANANA0.0740.2670.2870.307NANANANANANANANANANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
us-gaap:StockholdersEquity ██▇▇▇▆▆▅▅▅▄▃▃▂▂▁▁▁▁2846.8812773.7222674.9532619.2382611.2952547.8952505.9142423.712419.3632347.02252.0421946.2331933.0191879.5381814.7681715.6911716.5681715.3811663.49NANANA1594.408NANANANANANANA
us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest NANA2674.9532619.2382611.2952547.8952505.9142423.712419.3632346.5482251.591945.7811932.5671876.3761812.4031713.3961714.2561713.1191661.273NANANA1592.325NANANA1486.266NANANA
 us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest dei:LegalEntity swx:SouthwestGasCorporation██▆▆▆▆▅▄▄▄▃▂▂▂▂▁▁▁▂2429.7362374.1242233.4682144.2732151.9772114.2762005.1521929.6061948.2221887.9031782.461719.9271718.9931679.1441609.9991530.4011541.641550.3391667.88NANANA1593.186NANANANANANANA
 us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest dei:LegalEntity,us-gaap:StatementEquityComponents swx:SouthwestGasCorporation,us-gaap:AdditionalPaidInCapital█▇▇▆▆▅▅▄▄▃▃▃▂▂▂▁▁▁▁1529.4191458.3441410.3451363.4411329.8431279.2081229.0831194.7451169.5491089.0021065.2421041.311006.065948.199948.767917.581904.715903.252897.346NANANA890.671NANANANANANANA
 us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest dei:LegalEntity,us-gaap:StatementEquityComponents swx:SouthwestGasCorporation,us-gaap:CommonStock▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄49.11249.11249.11249.11249.11249.11249.11249.11249.11249.11249.11249.11249.11249.11249.11249.11249.11249.11249.112NANANA49.007NANANANANANANA
 us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest dei:LegalEntity,us-gaap:StatementEquityComponents swx:SouthwestGasCorporation,us-gaap:RetainedEarnings██▆▅▆▆▅▄▅▅▃▃▃▄▂▁▂▂▅908.757926.011835.146781.735824.847839.443782.108731.036776.101797.584717.155681.284717.126736.676659.193606.007631.226642.501767.061NANANA701.251NANANANANANANA
 us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest us-gaap:StatementEquityComponents us-gaap:AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterest█▄▁1.8640.9550.132NANANA-1.581NANANA-3.619NANANA-0.609NANANANANANANANANANANANANANANA
 us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest us-gaap:StatementEquityComponents us-gaap:AccumulatedTranslationAdjustmentNANANA-2.768-3.792-5.586-1.581-2.488-2.041-2.828-3.619-1.611NANA-0.609NANANANANANANANANANANANANANANA
 us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest us-gaap:StatementEquityComponents us-gaap:AdditionalPaidInCapital█▇▇▇▆▆▆▆▅▅▄▂▂▂▁▁▁▁▁1733.5721660.1081609.1551559.8141523.631470.4111466.9371437.7331409.9231332.7931305.7691045.841021.508965.48955.332924.213911.095909.362903.123NANANA896.448NANANA851.381NANANA
 us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest us-gaap:StatementEquityComponents us-gaap:CommonStock█▇▇▆▆▆▆▅▅▅▄▂▂▂▁▁▁▁▁60.71859.62558.82358.08957.5456.75656.63756.25455.95155.02154.65651.05350.75649.96749.7249.36249.21349.17949.112NANANA49.007NANANA48.153NANANA
 us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest us-gaap:StatementEquityComponents us-gaap:Parent█▇▇▆▆▆▅▅▅▄▃▁▁2846.8812773.7222674.9532619.2382611.2952547.8952505.9142423.712419.3632347.02252.0421946.2331933.019NA1814.768NANANANANANANANANANANANANANANA
 us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest us-gaap:StatementEquityComponents us-gaap:RetainedEarnings██▇▇▇▇▇▅▆▆▅▄▄▄▃▂▂▂▁1108.2791112.3771067.9781054.1181085.7421079.8011039.072977.4981002.071009.809944.285902.73916.275920.454857.398784.934801.222803.522759.263NANANA699.221NANANA639.164NANANA
us-gaap:CommonStockValue █▇▇▆▆▆▆▅▅▅▄▂▂▂▁▁▁▁▁60.71859.62558.82358.08957.5456.75656.63756.25455.95155.02154.65651.05350.75649.96749.7249.36249.21349.17949.112NANANA49.007NANANANANANANA
us-gaap:AdditionalPaidInCapitalCommonStock █▇▇▇▆▆▆▆▅▅▄▂▂▂▁▁▁▁▁1733.5721660.1081609.1551559.8141523.631470.4111466.9371437.7331409.9231332.7931305.7691045.841021.508965.48955.332924.213911.095909.362903.123NANANA896.448NANANANANANANA
us-gaap:RetainedEarningsAccumulatedDeficit ██▇▇▇▇▇▅▆▆▅▄▄▄▃▂▂▂▁1108.2791112.3771067.9781054.1181085.7421079.8011039.072977.4981002.071009.809944.285902.73916.275920.454857.398784.934801.222803.522759.263NANANA699.221NANANANANANANA
us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax ▃▂▁▄▃▂▃▆▆▅▄▄▃▃▆█▇▇▆-55.688-58.388-61.003-52.783-55.617-59.073-56.732-47.775-48.581-50.623-52.668-53.39-55.52-56.363-47.682-42.818-44.962-46.682-48.008NANANA-50.268NANANANANANANA
 us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax dei:LegalEntity swx:SouthwestGasCorporation▂▂▁▅▄▄▃▇▆▆▅▄▄▃▆██▇▇-57.552-59.343-61.135-50.015-51.825-53.487-55.151-45.287-46.54-47.795-49.049-51.779-53.31-54.843-47.073-42.299-43.413-44.526-45.639NANANANANANANANANANANA
 us-gaap:StockIssuedDuringPeriodValueNewIssues us-gaap:PlanName swx:DividendReinvestmentAndStockPurchasePlan▄▅▁▅▄▅█▃▄▄2.73.12.03.02.93.13.92.62.72.8NANANANANANANANANANANANANANANANANANANANA
 us-gaap:StockIssuedDuringPeriodValueNewIssues us-gaap:StatementEquityComponents us-gaap:AdditionalPaidInCapital▃▂▂▂▂▁▂▂▃▂█▂▂▁▂▁▁▁73.46450.95349.34136.18453.2193.47429.20427.8177.58227.024259.92924.33256.02810.14831.11913.1181.7336.239NANANANANANANANANANANANA
 us-gaap:StockIssuedDuringPeriodValueNewIssues us-gaap:StatementEquityComponents us-gaap:CommonStock▃▃▂▂▂▁▂▂▃▂█▂▂▁▂▁▁▁1.0930.8020.7340.5490.7840.1190.3830.3030.930.3653.6030.2970.7890.2470.3580.1490.0340.067NANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
us-gaap:NetCashProvidedByUsedInOperatingActivities ▃▁▅▅▄█▅▄▄▆▅▆▄▆▄▄53.814-52.457138.262112.678103.574271.566121.886100.0790.305188.111121.463160.37166.455180.56770.711101.052NANANANANANANANANANANANANANA
us-gaap:NetCashProvidedByUsedInInvestingActivities ▇█▇▇▆▇▆▆▅▇▁▆▇█▅▇-176.523-144.86-183.556-203.971-213.751-200.791-240.624-230.539-273.147-207.322-449.987-216.998-178.29-154.208-258.096-186.03NANANANANANANANANANANANANANA
 us-gaap:NetCashProvidedByUsedInInvestingActivities dei:LegalEntity swx:SouthwestGasCorporation▆█▅▅▄▅▃▁▃▅▃▃▆█-144.216-124.38-160.065-167.044-182.352-167.951-187.435-216.59-195.181-160.636-195.722-196.607-148.651-128.412NANANANANANANANANANANANANANANANA
us-gaap:NetCashProvidedByUsedInFinancingActivities ▄▆▄▁▆▁▅▄▄▃█▄▄▂▅▄77.844206.207104.264-84.314248.658-59.034139.697120.517124.24430.822345.06290.80481.503-4.795171.837114.288NANANANANANANANANANANANANANA
us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect ▄▅▆▁█▅▅▅▄▅▅▆▄▅▅▆-44.788.99359.407-175.646138.62611.42621.059-9.966-58.59111.67616.19134.44-30.38521.493-15.5329.45NANANANANANANANANANANANANANA
 us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect dei:LegalEntity swx:SouthwestGasCorporation▅▅▅▁█▅▅▅▄▆▅▆▄▅▅▅-12.0778.72518.836-168.55134.2616.03523.678-15.632-42.70543.186-17.10328.165-24.8897.843-8.52124.023NANANANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
us-gaap:IncreaseDecreaseInAccountsPayable ▅▂▇▄▅▁▇▅▂▄█▄▅▂▇▆▅▁▇▅▅▂0.072-41.14751.337-11.83313.525-60.72344.2142.076-35.512-12.64360.396-4.1534.032-48.49746.73223.6764.851-55.29846.6378.4161.768-35.126NANANANANANANANA
us-gaap:IncreaseDecreaseInAccountsReceivable ▆▁▅▆█▁▇▅▃▅▅▃▆▄▆▅▆▂▄▆▄▁32.887-42.8926.63332.39355.583-45.83734.6317.003-12.9515.56214.203-11.04521.562-8.85825.61718.87533.344-36.889-1.56524.376-7.382-45.525NANANANANANANANA
us-gaap:NetCashProvidedByUsedInOperatingActivities ▃▁▅▅▄█▅▄▄▆▅▆▄▆▄▄53.814-52.457138.262112.678103.574271.566121.886100.0790.305188.111121.463160.37166.455180.56770.711101.052NANANANANANANANANANANANANANA
us-gaap:NetIncomeLoss ▃█▇▂▃▅▇▂▃▇▅▂▃▆▇▂▂▅▅▁▂▆▅▁▂▅▅▁▂▅25.119117.293103.54418.27337.96572.54291.7185.35322.05694.80969.30412.33121.55179.09196.46510.20417.86469.30865.182.4728.94375.44666.119-4.7344.94971.98358.7461.979.62770.783
us-gaap:ProfitLoss ▃▇▇▂▃▅▆▂▂▆█▂▂▅▆▂▂▅▅▁▂▅▅▁▁▅▄▁▂▅26.474118.845105.03621.06339.88173.00591.9066.52522.83295.384131.1612.33121.55178.29496.39610.4218.12169.00565.6942.9079.09975.35566.698-4.215.06371.87958.8971.9279.62770.697
us-gaap:ShareBasedCompensation ▃▅▂▂▂▄▁▂▂▄▂▂▂▂▂▂▂█▁▁▃▂2.0783.6581.3251.4571.5162.8160.8291.3651.5143.1881.4251.3861.4391.8611.6891.4681.626.1111.1090.8332.121.394NANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
us-gaap:NetCashProvidedByUsedInInvestingActivities ▇█▇▇▆▇▆▆▅▇▁▆▇█▅▇-176.523-144.86-183.556-203.971-213.751-200.791-240.624-230.539-273.147-207.322-449.987-216.998-178.29-154.208-258.096-186.03NANANANANANANANANANANANANANA
 us-gaap:NetCashProvidedByUsedInInvestingActivities dei:LegalEntity swx:SouthwestGasCorporation▆█▅▅▄▅▃▁▃▅▃▃▆█-144.216-124.38-160.065-167.044-182.352-167.951-187.435-216.59-195.181-160.636-195.722-196.607-148.651-128.412NANANANANANANANANANANANANANANANA
us-gaap:PaymentsToAcquirePropertyPlantAndEquipment ▄▃▅▆▆▆▆▇█▆▅▆▄▃▄▅▃▁▂▂▃▁185.34152.709192.631209.039212.78210.655218.762247.808260.916210.662205.749221.154184.469154.542173.651187.764146.444115.79125.143139.516152.311112.561NANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
us-gaap:NetCashProvidedByUsedInFinancingActivities ▄▆▄▁▆▁▅▄▄▃█▄▄▂▅▄77.844206.207104.264-84.314248.658-59.034139.697120.517124.24430.822345.06290.80481.503-4.795171.837114.288NANANANANANANANANANANANANANA
us-gaap:ProceedsFromIssuanceOfLongTermDebt ▂▁▁▁█▂▂▂▆▁▂▁▃▅▅▁▂▁▁▅▁▂71.58610.65911.75830.316520.32599.97848.98261.02391.92829.66684.17925.595120.016335.382302.75523.72954.29926.2815.0312.81846.75349.375NANANANANANANANA
us-gaap:RepaymentsOfLongTermDebt ▂▁▃▆▂▃▃▃▁▂▄▂▃▁█▂▁▂▂▅▁▂39.27221.22867.111171.75942.36875.16886.61473.57122.44431.1694.00142.98179.67421.102238.72940.19912.27847.76358.922143.38510.65442.312NANANANANANANANA
us-gaap:PaymentsOfDividendsCommonStock █▇▇▇▇▆▆▆▆▅▄▄▄▃▃▃▃▂▂▂▂▁34.51132.61932.18731.87231.43930.00629.78229.60729.13627.60225.70525.5525.14623.83923.62723.55423.55221.39721.36721.36721.36319.22NANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31

Common Stock Value

us-gaap:CommonStockValue

us-gaap:CommonStockValue


Common
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value6059585857565656555554515049494949494949
Percentage of CommonStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.70.70.70.70.70.70.70.70.70.70.70.80.80.80.80.80.90.90.90.9

Common Stock Shares Outstanding

us-gaap:CommonStockSharesOutstanding dei:LegalEntity, us-gaap:StatementEquityComponents

us-gaap:CommonStockSharesOutstanding

swx:SouthwestGasCorporation, us-gaap:CommonStock


Common
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value4747474747474747474747474747474747474747
Percentage of CommonStockSharesOutstanding100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CommonStockSharesOutstanding us-gaap:StatementEquityComponents

us-gaap:CommonStock


Common
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-312014-12-312013-12-31
Value59575756555555545453534949484847474747474646
Percentage of CommonStockSharesOutstanding124.4122.1120.5118.9117.7116.1115.8115.0114.4112.4111.7104.1103.5101.8101.3100.5100.2100.1100.0100.00.00.0

Weighted Average Number Of Diluted Shares Outstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding


Weighted
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-31
Value5857565555545453494848474747474747
Percentage of WeightedAverageNumberOfDilutedSharesOutstanding100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Weighted Average Number Of Shares Outstanding Basic

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic


Weighted
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-31
Value5857565555545353494848474747474747
Percentage of WeightedAverageNumberOfSharesOutstandingBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Earnings Per Share Basic

us-gaap:EarningsPerShareBasic

us-gaap:EarningsPerShareBasic


Earnings
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value0.432.041.820.320.681.311.670.10.411.781.360.250.441.632.00.210.381.461.370.050.191.591.4-0.10.111.541.260.040.211.52
Percentage of EarningsPerShareBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Earnings Per Share Diluted

us-gaap:EarningsPerShareDiluted

us-gaap:EarningsPerShareDiluted


Earnings
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value0.432.031.820.320.681.311.670.10.411.771.360.250.441.632.00.210.371.451.360.050.191.581.38-0.10.11.531.250.040.211.51
Percentage of EarningsPerShareDiluted100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Comprehensive Income Net Of Tax

us-gaap:ComprehensiveIncomeNetOfTax

us-gaap:ComprehensiveIncomeNetOfTax


Comprehensive
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value2711995214170826.15924967014227991121970633.3671077
Percentage of ComprehensiveIncomeNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue3.413.510.42.75.58.49.80.83.411.68.92.23.310.612.42.13.510.89.90.61.910.6

Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest

us-gaap:ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest

us-gaap:ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest


Comprehensive
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value1355000.01552000.01492000.02790000.01916000.0463000.0188000.01172000.0776000.0575000.0172000.000-797000.0-69000.0198000.0279000.0-296000.0498000.0427000.0159000.0-65000.0
Percentage of ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue0.20.20.20.40.30.10.00.20.10.10.00.00.0-0.1-0.00.00.0-0.00.10.10.0-0.0

Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest


Comprehensive
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value2912196234370827.33124977014227891121970633.7941077
Percentage of ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue3.613.710.63.05.78.49.81.03.511.78.92.23.310.512.42.13.510.710.00.71.910.6

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest dei:LegalEntity

swx:SouthwestGasCorporation


Comprehensive
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value1312068-14.163138566-18.7594.62410462-12.1394.1559169-2.91107850-11.283.48278
Percentage of ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest45.399.270.7-59.331.4120.780.2-255.918.6107.488.7-83.918.6116.476.0-23.253.5111.079.1-297.333.8101.9
Percentage of RegulatedAndUnregulatedOperatingRevenue1.613.67.5-1.81.810.27.8-2.60.612.67.9-1.80.612.29.4-0.51.911.97.9-2.10.610.8
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation0.00.018.3-6.75.217.017.5-8.91.820.116.8-5.61.518.619.0-1.44.116.97.9-2.10.610.8

Cost Of Goods And Services Sold

us-gaap:CostOfGoodsAndServicesSold

us-gaap:CostOfGoodsAndServicesSold


Cost
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value478335476502430319418451402300380395352258342342272
Percentage of CostOfGoodsAndServicesSold100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue58.337.952.263.656.838.249.462.356.436.048.359.252.634.346.257.848.5

Costs And Expenses

us-gaap:CostsAndExpenses

us-gaap:CostsAndExpenses


Costs
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value762712761736689687709686658693651628617624609563517535523524519597
Percentage of CostsAndExpenses100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue92.880.483.393.191.182.383.794.792.383.182.994.192.082.882.494.992.381.781.697.194.981.7

us-gaap:CostsAndExpenses dei:LegalEntity

swx:SouthwestGasCorporation


Costs
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value256351258209235345266211234371254217251353253207232331244210240389
Percentage of CostsAndExpenses33.749.333.928.434.150.237.630.835.753.739.034.640.656.541.636.945.061.946.740.146.365.2
Percentage of RegulatedAndUnregulatedOperatingRevenue31.239.728.326.431.141.331.529.232.944.632.332.637.446.834.235.141.550.638.139.043.953.2
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation0.00.069.099.289.768.670.3100.990.771.468.7100.091.071.469.297.689.471.738.139.043.953.2

Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value321491282749991129.666291209716261021141326104101-0.05412118
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue3.916.914.13.56.511.913.31.34.114.512.42.44.013.615.42.34.816.015.8-0.02.316.1

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest dei:LegalEntity

swx:SouthwestGasCorporation


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value1014894-22.7271011291-26.7792.31613182-19.562.43211799-9.2751211779-24.0741.144121
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest33.999.273.4-81.922.3113.180.6-277.07.9108.884.6-122.19.0114.387.0-68.646.8112.378.644581.59.3102.9
Percentage of RegulatedAndUnregulatedOperatingRevenue1.316.810.3-2.91.413.410.7-3.70.315.810.5-2.90.415.613.4-1.62.217.912.4-4.50.216.6
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation0.00.025.2-10.84.222.324.0-12.80.925.322.3-9.00.923.727.1-4.44.825.412.4-4.50.216.6

Income Tax Expense Benefit

us-gaap:IncomeTaxExpenseBenefit

us-gaap:IncomeTaxExpenseBenefit


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value5.54231236.6899.16626203.1416.35225283.6915.42924173.0948.6793535-2.9613.26642
Percentage of IncomeTaxExpenseBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue0.73.52.60.81.23.12.50.40.93.13.60.60.83.22.40.51.55.45.5-0.50.65.8

us-gaap:IncomeTaxExpenseBenefit dei:LegalEntity

swx:SouthwestGasCorporation


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-0.5593014-6.754-0.9942814-6.767-1.0532823-5.89-0.192624-5.2513.0284027-11.669-1.21443
Percentage of IncomeTaxExpenseBenefit-10.196.762.8-101.0-10.8109.269.7-215.4-16.6110.381.7-159.6-3.5111.0140.5-169.734.9113.777.9394.1-37.2102.7
Percentage of RegulatedAndUnregulatedOperatingRevenue-0.13.41.6-0.9-0.13.41.7-0.9-0.13.42.9-0.9-0.03.63.4-0.90.56.24.3-2.2-0.26.0
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation0.00.04.0-3.2-0.45.73.9-3.2-0.45.46.2-2.7-0.15.56.8-2.51.28.84.3-2.2-0.26.0

Income Taxes Paid Net

us-gaap:IncomeTaxesPaidNet

us-gaap:IncomeTaxesPaidNet


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value5.0081.6515.0553.4040.654-20.0642.381-1.4611.3780.454-17.041.754124.4181.9860.6441.2161.827-25.5621.7932.6012.136
Percentage of IncomeTaxesPaidNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue0.60.20.60.40.1-2.40.3-0.20.20.1-2.20.31.80.60.30.10.20.3-4.00.30.50.3

us-gaap:IncomeTaxesPaidNet dei:LegalEntity

swx:SouthwestGasCorporation


Income
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value3.3590.00.0-22.9620.70.00.0-0.022-17.1420.4100.0-7.858-0.0150.057-0.038-27.956
Percentage of IncomeTaxesPaidNet66.40.00.0114.429.4-0.00.0-4.8100.622.890.00.0-395.7-2.34.7-2.1109.4
Percentage of RegulatedAndUnregulatedOperatingRevenue0.40.00.0-2.70.10.00.0-0.0-2.20.11.60.0-1.1-0.00.0-0.0-4.4
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation0.90.00.0-4.60.20.00.0-0.0-4.60.23.90.0-2.1-0.00.0-0.0-4.4

Interest Expense

us-gaap:InterestExpense

us-gaap:InterestExpense


Interest
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value25232828262828272626252423222119181819181817
Percentage of InterestExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue3.22.73.13.63.53.43.43.83.83.23.33.73.53.02.93.33.32.93.03.43.32.4

us-gaap:InterestExpense dei:LegalEntity

swx:SouthwestGasCorporation


Interest
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value24222526232524232323212020191817161717161616
Percentage of InterestExpense93.292.591.792.290.788.387.486.187.087.584.983.185.285.185.489.491.192.091.290.190.991.6
Percentage of RegulatedAndUnregulatedOperatingRevenue2.92.52.83.33.23.02.93.33.32.82.83.13.02.62.42.93.02.62.83.03.02.2
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation0.00.06.912.49.15.06.611.29.04.45.99.47.33.94.98.26.53.72.83.03.02.2

Interest Paid Net

us-gaap:InterestPaidNet

us-gaap:InterestPaidNet


Interest
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value398.3034112381340123415369.48626132610241020132210
Percentage of InterestPaidNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue4.80.94.51.65.11.64.71.74.81.94.71.44.01.83.51.84.41.63.22.64.11.4

us-gaap:InterestPaidNet dei:LegalEntity

swx:SouthwestGasCorporation


Interest
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value376.95239103610368.8673111309.5342310248.546238.98918
Percentage of InterestPaidNet96.783.795.586.094.878.192.172.991.673.183.3100.586.477.491.980.793.387.492.1
Percentage of RegulatedAndUnregulatedOperatingRevenue4.60.84.31.34.81.24.41.24.41.43.91.43.51.43.21.44.11.42.9
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation0.00.010.65.013.92.09.74.212.12.28.34.48.42.16.64.08.91.92.9

Net Income Loss

us-gaap:NetIncomeLoss

us-gaap:NetIncomeLoss


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value25117103183772915.35322946912217996101769652.4728.9437566-4.7344.94971581.979.62770
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue3.113.211.32.35.08.710.80.73.111.48.81.83.210.513.01.73.210.610.20.51.610.39.6-0.90.99.89.40.52.111.6

us-gaap:NetIncomeLoss dei:LegalEntity

swx:SouthwestGasCorporation


Net
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value11118-15.9731183-20.0123.36910359-13.672.6229074-4.0249.52276652.4728.9437566-4.7344.94971
Percentage of NetIncomeLoss45.4101.2-87.431.5115.2-373.815.3109.085.9-110.912.2114.277.1-39.453.3111.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue1.413.4-2.01.610.0-2.80.512.47.6-2.00.412.010.0-0.71.711.810.20.51.610.39.6-0.90.99.8
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation0.00.0-7.64.616.6-9.51.319.916.1-6.31.018.320.3-1.93.716.610.20.51.610.39.6-0.90.99.8

us-gaap:NetIncomeLoss us-gaap:ConsolidationItems

us-gaap:MaterialReconcilingItems


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-1.41-0.5630.068-0.627-0.244-0.853-0.386-0.473-0.231-0.549-0.18-0.797-0.307-0.257-0.56-0.107
Percentage of NetIncomeLoss-5.6-0.50.1-3.4-0.6-1.2-0.4-8.8-1.0-0.6-0.3-6.5-1.4-0.3-0.6-1.0
Percentage of RegulatedAndUnregulatedOperatingRevenue-0.2-0.10.0-0.1-0.0-0.1-0.0-0.1-0.0-0.1-0.0-0.1-0.0-0.0-0.1-0.0
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:MaterialReconcilingItems0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:NetIncomeLoss us-gaap:StatementBusinessSegments

swx:NaturalGasOperations


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value1111879-15.973118376-20.0123.36910359-13.672.6229074-4.0249.5227651-12.4052.35877
Percentage of NetIncomeLoss45.4101.276.8-87.431.5115.283.3-373.815.3109.085.9-110.912.2114.277.1-39.453.3111.079.6-501.826.4102.8
Percentage of RegulatedAndUnregulatedOperatingRevenue1.413.48.7-2.01.610.09.0-2.80.512.47.6-2.00.412.010.0-0.71.711.88.1-2.30.410.6
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:NaturalGasOperations0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

swx:UtilityInfrastructureServicesSegment


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value15-0.859233426-10.204152518-8.0319.9432619-11.001
Percentage of NetIncomeLoss60.2-0.723.1190.869.2-14.117.1482.785.8-8.514.3217.389.3-13.9
Percentage of RegulatedAndUnregulatedOperatingRevenue1.8-0.12.64.43.5-1.21.83.62.7-1.01.34.02.9-1.5
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:UtilityInfrastructureServicesSegment0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Net Income Loss Attributable To Noncontrolling Interest

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value1355000.01552000.01492000.02790000.01916000.0463000.0188000.01172000.0776000.0575000.0172000.000-797000.0-69000.0216000.0257000.0-303000.0514000.0435000.0156000.0-91000.0
Percentage of NetIncomeLossAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue0.20.20.20.40.30.10.00.20.10.10.00.00.0-0.1-0.00.00.0-0.00.10.10.0-0.0

Nonoperating Income Expense

us-gaap:NonoperatingIncomeExpense

us-gaap:NonoperatingIncomeExpense


Nonoperating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-27250000.0-23516000.0-24079000.0-26512000.0-18525000.0-49150000.0-25306000.0-28592000.0-25685000.0-19558000.0-37115000.0-23659000.0-26358000.0-26965000.0-16595000.0-16618000.0-16608000.0-14849000.0-16847000.0-15593000.0-15751000.0-16000000.0
Percentage of NonoperatingIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue-3.3-2.7-2.6-3.4-2.4-5.9-3.0-3.9-3.6-2.3-4.7-3.5-3.9-3.6-2.2-2.8-3.0-2.3-2.6-2.9-2.9-2.2

us-gaap:NonoperatingIncomeExpense dei:LegalEntity

swx:SouthwestGasCorporation


Nonoperating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-25340000.0-21616000.0-21639000.0-24352000.0-16153000.0-45594000.0-21631000.0-24972000.0-21753000.0-17153000.0-33316000.0-19563000.0-22243000.0-23858000.0-13819000.0-14340000.0-14939000.0-13599000.0-16278000.0-13843000.0-14125000.0-14475000.0
Percentage of NonoperatingIncomeExpense93.091.989.991.987.292.885.587.384.787.789.882.784.488.583.386.390.091.696.688.889.790.5
Percentage of RegulatedAndUnregulatedOperatingRevenue-3.1-2.4-2.4-3.1-2.1-5.5-2.6-3.4-3.1-2.1-4.2-2.9-3.3-3.2-1.9-2.4-2.7-2.1-2.5-2.6-2.6-2.0
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation0.00.0-5.8-11.6-6.2-9.1-5.7-11.9-8.4-3.3-9.0-9.0-8.1-4.8-3.8-6.7-5.7-2.9-2.5-2.6-2.6-2.0

Operating Income Loss

us-gaap:OperatingIncomeLoss

us-gaap:OperatingIncomeLoss


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value591731525467148138385414013439531291303043119117152813411716251291121826127
Percentage of OperatingIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue7.219.616.76.98.917.716.35.37.716.917.15.98.017.217.65.17.718.318.42.95.118.317.23.24.717.617.94.25.920.9

us-gaap:OperatingIncomeLoss dei:LegalEntity

swx:SouthwestGasCorporation


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value361701161.62527157112-1.807241481150.003241411175.06527131117-10.231151351171625129
Percentage of OperatingIncomeLoss61.198.276.03.040.1106.481.5-4.743.9105.986.00.046.3109.090.216.863.3109.7100.0-65.854.3101.4100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue4.419.212.70.23.618.913.3-0.23.417.814.70.03.718.715.90.94.920.018.4-1.92.818.617.23.24.717.6
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation0.00.031.00.810.331.429.7-0.99.328.631.30.09.028.632.22.410.628.318.4-1.92.818.617.23.24.717.6

Other Comprehensive Income Loss Cash Flow Hedge Gain Loss After Reclassification And Tax

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-30
Value414000.0413000.0413000.0783000.0635000.0636000.0635000.0635000.0636000.0
Percentage of OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue0.10.00.00.10.10.10.10.10.1

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax dei:LegalEntity

swx:SouthwestGasCorporation


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-30
Value414000.0413000.0413000.0783000.0635000.0636000.0635000.0635000.0636000.0
Percentage of OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTax100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue0.10.00.00.10.10.10.10.10.1
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation0.00.00.10.40.20.10.20.30.2

Other Comprehensive Income Loss Foreign Currency Transaction And Translation Adjustment Net Of Tax

us-gaap:OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax

us-gaap:OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value909000.0823000.02900000.01024000.01794000.0-4005000.0907000.0-447000.0787000.0791000.0-2008000.0599000.0-690000.0-911000.0-90000.01012000.0629000.0220000.0-453000.0-238000.070000.0782000.0
Percentage of OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue0.10.10.30.10.2-0.50.1-0.10.10.1-0.30.1-0.1-0.1-0.00.20.10.0-0.1-0.00.00.1

Other Comprehensive Income Loss Net Of Tax

us-gaap:OtherComprehensiveIncomeLossNetOfTax

us-gaap:OtherComprehensiveIncomeLossNetOfTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value2.72.615-8.222.8343.456-2.341-8.9570.8062.0422.0450.7222.130.8430.619-4.8642.1261.7421.333-1.7240.8871.1941.908
Percentage of OtherComprehensiveIncomeLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue0.30.3-0.90.40.5-0.3-1.10.10.30.20.10.30.10.1-0.70.40.30.2-0.30.20.20.3

us-gaap:OtherComprehensiveIncomeLossNetOfTax dei:LegalEntity

swx:SouthwestGasCorporation


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value1.7911.792-11.121.811.6621.664-9.8641.2531.2551.2542.731.5311.5331.53-4.7741.1141.1131.113-1.2711.1251.1241.126
Percentage of OtherComprehensiveIncomeLossNetOfTax66.368.5135.363.948.1-71.1110.1155.561.561.3378.171.9181.9247.298.152.463.983.573.7126.894.159.0
Percentage of RegulatedAndUnregulatedOperatingRevenue0.20.2-1.20.20.20.2-1.20.20.20.20.30.20.20.2-0.60.20.20.2-0.20.20.20.2
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation0.00.0-3.00.90.60.3-2.60.60.50.20.70.70.60.3-1.30.50.40.2-0.20.20.20.2

us-gaap:OtherComprehensiveIncomeLossNetOfTax dei:LegalEntity, us-gaap:StatementEquityComponents

swx:SouthwestGasCorporation, swx:AccumulatedDefinedBenefitPlansAdjustmentRegulartoryAdjustmentAttributabletoParent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value-7.277-7.27724-6.38-6.38-6.3840-4.065-4.065-4.06310
Percentage of OtherComprehensiveIncomeLossNetOfTax-269.5-278.3-301.6-225.1-184.6272.5-449.6-504.3-199.1-198.71520.6
Percentage of RegulatedAndUnregulatedOperatingRevenue-0.9-0.82.7-0.8-0.8-0.84.7-0.6-0.6-0.51.4
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation swx:AccumulatedDefinedBenefitPlansAdjustmentRegulartoryAdjustmentAttributabletoParent0.00.00.00.00.00.00.00.00.00.00.0

swx:SouthwestGasCorporation, us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value1.3771.379-11.5331.0271.0271.028-10.4990.6180.6190.6192.096
Percentage of OtherComprehensiveIncomeLossNetOfTax51.052.7140.336.229.7-43.9117.276.730.330.3290.3
Percentage of RegulatedAndUnregulatedOperatingRevenue0.20.2-1.30.10.10.1-1.20.10.10.10.3
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation us-gaap:AccumulatedDefinedBenefitPlansAdjustment0.00.00.00.00.00.00.00.00.00.00.0

swx:SouthwestGasCorporation, us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCredit


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value0.1820.1820.2190.2190.220.220.2420.2410.2420.2410.253
Percentage of OtherComprehensiveIncomeLossNetOfTax6.77.0-2.77.76.4-9.4-2.729.911.911.835.0
Percentage of RegulatedAndUnregulatedOperatingRevenue0.00.00.00.00.00.00.00.00.00.00.0
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCredit0.00.00.00.00.00.00.00.00.00.00.0

swx:SouthwestGasCorporation, us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLoss


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value8.4728.4747.1887.1887.1877.1884.4414.4424.4424.4416.388
Percentage of OtherComprehensiveIncomeLossNetOfTax313.8324.1-87.4253.6208.0-307.0-49.6551.1217.5217.2884.8
Percentage of RegulatedAndUnregulatedOperatingRevenue1.01.00.80.90.90.90.50.60.60.50.8
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLoss0.00.00.00.00.00.00.00.00.00.00.0

swx:SouthwestGasCorporation, us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value0.4140.4130.4130.7830.6350.6360.6350.6350.6360.6350.634
Percentage of OtherComprehensiveIncomeLossNetOfTax15.315.8-5.027.618.4-27.2-7.178.831.131.187.8
Percentage of RegulatedAndUnregulatedOperatingRevenue0.10.00.00.10.10.10.10.10.10.10.1
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent0.00.00.00.00.00.00.00.00.00.00.0

us-gaap:OtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents

swx:AccumulatedDefinedBenefitPlansAdjustmentRegulartoryAdjustmentAttributabletoParent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value-7.277-7.27724-6.38-6.38-6.3840-4.065-4.065-4.06310
Percentage of OtherComprehensiveIncomeLossNetOfTax-269.5-278.3-301.6-225.1-184.6272.5-449.6-504.3-199.1-198.71520.6
Percentage of RegulatedAndUnregulatedOperatingRevenue-0.9-0.82.7-0.8-0.8-0.84.7-0.6-0.6-0.51.4
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:AccumulatedDefinedBenefitPlansAdjustmentRegulartoryAdjustmentAttributabletoParent0.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value1.3771.379-11.5331.0271.0271.028-10.4990.6180.6190.6192.0960.8950.8970.895-5.2930.596
Percentage of OtherComprehensiveIncomeLossNetOfTax51.052.7140.336.229.7-43.9117.276.730.330.3290.342.0106.4144.6108.828.0
Percentage of RegulatedAndUnregulatedOperatingRevenue0.20.2-1.30.10.10.1-1.20.10.10.10.30.10.10.1-0.70.1
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:AccumulatedDefinedBenefitPlansAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCredit


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value0.1820.1820.2190.2190.220.220.2420.2410.2420.2410.253
Percentage of OtherComprehensiveIncomeLossNetOfTax6.77.0-2.77.76.4-9.4-2.729.911.911.835.0
Percentage of RegulatedAndUnregulatedOperatingRevenue0.00.00.00.00.00.00.00.00.00.00.0
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCredit0.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLoss


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value8.4728.4747.1887.1887.1877.1884.4414.4424.4424.4416.388
Percentage of OtherComprehensiveIncomeLossNetOfTax313.8324.1-87.4253.6208.0-307.0-49.6551.1217.5217.2884.8
Percentage of RegulatedAndUnregulatedOperatingRevenue1.01.00.80.90.90.90.50.60.60.50.8
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLoss0.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedTranslationAdjustment


Other
Period End2020-09-302020-06-302020-03-312019-09-302019-06-302019-03-31
Value1.0241.794-4.005-0.4470.7870.791
Percentage of OtherComprehensiveIncomeLossNetOfTax36.151.9171.1-55.538.538.7
Percentage of RegulatedAndUnregulatedOperatingRevenue0.10.2-0.5-0.10.10.1
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:AccumulatedTranslationAdjustment0.00.00.00.00.00.0

us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value0.4140.4130.4130.7830.6350.6360.6350.6350.6360.6350.6340.6360.6360.6350.5190.518
Percentage of OtherComprehensiveIncomeLossNetOfTax15.315.8-5.027.618.4-27.2-7.178.831.131.187.829.975.4102.6-10.724.4
Percentage of RegulatedAndUnregulatedOperatingRevenue0.10.00.00.10.10.10.10.10.10.10.10.10.10.10.10.1
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Other Nonoperating Income Expense

us-gaap:OtherNonoperatingIncomeExpense

us-gaap:OtherNonoperatingIncomeExpense


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-1.3110.4484.2571.7997.925-20.773.258-1.1581.1466.839-11.2750.889-2.706-4.3344.6062.8762.0473.8652.7132.5652.471.721
Percentage of OtherNonoperatingIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue-0.20.10.50.21.0-2.50.4-0.20.20.8-1.40.1-0.4-0.60.60.50.40.60.40.50.50.2

us-gaap:OtherNonoperatingIncomeExpense dei:LegalEntity

swx:SouthwestGasCorporation


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-1.1650.554.3571.7517.838-20.5363.332-1.3531.5925.946-11.3790.836-2.094-4.6034.2923.0812.0523.6111.5642.5212.4361.755
Percentage of OtherNonoperatingIncomeExpense88.9122.8102.397.398.998.9102.3116.8138.986.9100.994.077.4106.293.2107.1100.293.457.698.398.6102.0
Percentage of RegulatedAndUnregulatedOperatingRevenue-0.10.10.50.21.0-2.50.4-0.20.20.7-1.40.1-0.3-0.60.60.50.40.60.20.50.40.2
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation0.00.01.20.83.0-4.10.9-0.60.61.1-3.10.4-0.8-0.91.21.40.80.80.20.50.40.2

us-gaap:OtherNonoperatingIncomeExpense dei:LegalEntity, us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

swx:CenturiGroupInc., us-gaap:OperatingSegments, swx:UtilityInfrastructureServicesSegment


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-0.146-0.102-0.10.0480.087-0.242-0.1030.171-0.4770.8750.0930.038-0.6320.263
Percentage of OtherNonoperatingIncomeExpense11.1-22.8-2.32.71.11.2-3.2-14.8-41.612.8-0.84.323.4-6.1
Percentage of RegulatedAndUnregulatedOperatingRevenue-0.0-0.0-0.00.00.0-0.0-0.00.0-0.10.10.00.0-0.10.0
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:CenturiGroupInc. us-gaap:OperatingSegments swx:UtilityInfrastructureServicesSegment0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

swx:SouthwestGasCorporation, us-gaap:OperatingSegments, swx:NaturalGasOperations


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-1.1650.554.3571.7517.838-20.5363.332-1.3531.5925.946-11.3790.836-2.094-4.603-0.564-1.775
Percentage of OtherNonoperatingIncomeExpense88.9122.8102.397.398.998.9102.3116.8138.986.9100.994.077.4106.2-12.2-61.7
Percentage of RegulatedAndUnregulatedOperatingRevenue-0.10.10.50.21.0-2.50.4-0.20.20.7-1.40.1-0.3-0.6-0.1-0.3
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation us-gaap:OperatingSegments swx:NaturalGasOperations0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:OtherNonoperatingIncomeExpense us-gaap:ConsolidationItems

us-gaap:CorporateNonSegment


Other
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value0.00.00.00.0080.0290.0240.0310.0180.0110.0150.020.0060.0070.005
Percentage of OtherNonoperatingIncomeExpense0.00.00.0-0.00.9-2.12.70.3-0.11.7-0.7-0.10.20.2
Percentage of RegulatedAndUnregulatedOperatingRevenue0.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:CorporateNonSegment0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Profit Loss

us-gaap:ProfitLoss

us-gaap:ProfitLoss


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value26118105213973916.525229513112217896101869652.9079.0997566-4.215.06371581.9279.62770
Percentage of ProfitLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue3.213.411.52.75.38.710.80.93.211.416.71.83.210.413.01.83.210.510.20.51.710.39.7-0.80.99.89.40.42.111.6

us-gaap:ProfitLoss dei:LegalEntity

swx:SouthwestGasCorporation


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value1111879-15.973118376-20.0123.36910359-13.672.6229074-4.0249.52276657.422.35877
Percentage of ProfitLoss43.199.975.7-75.829.9114.583.2-306.714.8108.445.4-110.912.2115.477.2-38.652.5111.5100.0255.225.9103.0
Percentage of RegulatedAndUnregulatedOperatingRevenue1.413.48.7-2.01.610.09.0-2.80.512.47.6-2.00.412.010.0-0.71.711.810.21.40.410.6
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation0.00.021.2-7.64.616.620.1-9.51.319.916.1-6.31.018.320.3-1.93.716.610.21.40.410.6

Regulated And Unregulated Operating Revenue

us-gaap:RegulatedAndUnregulatedOperatingRevenue

us-gaap:RegulatedAndUnregulatedOperatingRevenue


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value821885914791757836848725713833786668670754740593560654641539547731685505538734627432453608
Percentage of RegulatedAndUnregulatedOperatingRevenue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RegulatedAndUnregulatedOperatingRevenue dei:LegalEntity

swx:SouthwestGasCorporation


Regulated
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value374210262502379209258520370217275494366213260462641539547731685505538734
Percentage of RegulatedAndUnregulatedOperatingRevenue41.026.634.760.144.829.036.362.547.132.641.165.549.535.946.470.7100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue41.026.634.760.144.829.036.362.547.132.641.165.549.535.946.470.7100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Revenue From Contract With Customer Excluding Assessed Tax

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value291535914203259504848200253552786196261478740202537465641512521709685505538734627432453608
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue35.560.4100.025.734.260.4100.027.635.566.2100.029.539.063.4100.034.195.971.1100.095.095.397.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax dei:LegalEntity

swx:CenturiGroupInc.


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value528363539580494333468515454312416450395260
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax181.468.059.0285.8191.066.155.2257.3179.356.752.9228.9151.054.3
Percentage of RegulatedAndUnregulatedOperatingRevenue64.441.159.073.465.339.955.271.063.737.552.967.458.934.5
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:CenturiGroupInc.0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax dei:LegalEntity, us-gaap:ContractWithCustomerBasisOfPricing

swx:CenturiGroupInc., swx:BidContract


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1297012614211969106104787714610210565
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax44.613.113.870.246.113.912.652.431.014.018.752.040.213.7
Percentage of RegulatedAndUnregulatedOperatingRevenue15.87.913.818.015.88.412.614.511.09.318.715.315.78.7
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:CenturiGroupInc. swx:BidContract0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

swx:CenturiGroupInc., swx:MasterServicesAgreement


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value398293413437375263361410375235269348290194
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax136.854.845.2215.6144.952.242.6204.9148.342.734.3176.9110.840.6
Percentage of RegulatedAndUnregulatedOperatingRevenue48.533.245.255.349.631.542.656.652.728.334.352.143.225.8
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:CenturiGroupInc. swx:MasterServicesAgreement0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

swx:CenturiGroupInc., swx:UnitPricedContracts


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value361234370377365243373415355235309368329197
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax124.243.840.6185.8141.048.244.1207.4140.342.739.4187.4125.841.2
Percentage of RegulatedAndUnregulatedOperatingRevenue44.126.540.647.748.229.144.157.349.928.339.455.249.126.2
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:CenturiGroupInc. swx:UnitPricedContracts0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

swx:CenturiGroupInc., us-gaap:FixedPriceContract


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value50344746362732374.4263872452725
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax17.36.55.222.813.95.53.818.71.77.09.223.110.35.3
Percentage of RegulatedAndUnregulatedOperatingRevenue6.13.95.25.94.83.33.85.20.64.69.26.84.03.4
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:CenturiGroupInc. us-gaap:FixedPriceContract0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

swx:CenturiGroupInc., us-gaap:TimeAndMaterialsContract


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1169412015693626262943834363837
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax39.917.713.277.236.112.47.431.137.27.04.418.414.97.8
Percentage of RegulatedAndUnregulatedOperatingRevenue14.210.713.219.812.47.57.48.613.24.64.45.45.84.9
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:CenturiGroupInc. us-gaap:TimeAndMaterialsContract0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax dei:LegalEntity, us-gaap:ProductOrService

swx:CenturiGroupInc., swx:ElectricPowerInfrastructureServices


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value97939572
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax33.517.536.814.3
Percentage of RegulatedAndUnregulatedOperatingRevenue11.910.612.68.6
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:CenturiGroupInc. swx:ElectricPowerInfrastructureServices0.00.00.00.0

swx:CenturiGroupInc., swx:GasInfrastructureServices


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value346221330217
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax119.141.4127.443.1
Percentage of RegulatedAndUnregulatedOperatingRevenue42.225.043.626.0
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:CenturiGroupInc. swx:GasInfrastructureServices0.00.00.00.0

swx:CenturiGroupInc., swx:NewGasConstruction


Revenue
Period End2020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value11595727061524.6663.9945.402
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax56.836.814.335.324.29.52.41.51.1
Percentage of RegulatedAndUnregulatedOperatingRevenue14.612.68.69.78.66.30.70.60.7
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:CenturiGroupInc. swx:NewGasConstruction0.00.00.00.00.00.00.00.00.0

swx:CenturiGroupInc., swx:OtherConstruction


Revenue
Period End2020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value776943806962909061
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax38.126.88.640.127.311.345.834.712.8
Percentage of RegulatedAndUnregulatedOperatingRevenue9.89.25.211.19.77.513.513.58.1
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:CenturiGroupInc. swx:OtherConstruction0.00.00.00.00.00.00.00.00.0

swx:CenturiGroupInc., swx:OtherInfrastructureServices


Revenue
Period End2021-06-302021-03-312020-06-302020-03-31
Value84486943
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax28.99.026.88.6
Percentage of RegulatedAndUnregulatedOperatingRevenue10.25.49.25.2
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:CenturiGroupInc. swx:OtherInfrastructureServices0.00.00.00.0

swx:CenturiGroupInc., swx:ReplacementGasConstruction


Revenue
Period End2020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value387330217364323197355300193
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax190.8127.443.1181.9127.835.8180.7114.840.4
Percentage of RegulatedAndUnregulatedOperatingRevenue49.043.626.050.245.423.753.244.825.7
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:CenturiGroupInc. swx:ReplacementGasConstruction0.00.00.00.00.00.00.00.00.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:MajorCustomers

swx:IndustrialOrOther


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value6.974137.1535.8886.4996.7026.3463.8375.4136.4786.0985.395.4916.516.5085.0245.0435.451
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.42.60.82.92.51.30.71.92.11.20.82.72.11.40.92.50.91.2
Percentage of RegulatedAndUnregulatedOperatingRevenue0.81.60.80.70.90.80.70.50.80.80.80.80.80.90.90.80.90.8
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:IndustrialOrOther0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

swx:LargeCommercial


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value1312129.9429.97912121011131311131514111213
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.52.41.34.93.92.51.55.54.42.51.75.85.03.22.05.72.42.9
Percentage of RegulatedAndUnregulatedOperatingRevenue1.61.41.31.31.31.51.51.51.61.71.71.72.02.02.01.92.32.1
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:LargeCommercial0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

swx:Residential


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value193403267131181378266124164417255120166344232123158342
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax66.475.329.364.570.075.031.462.065.175.632.561.163.772.031.461.129.573.6
Percentage of RegulatedAndUnregulatedOperatingRevenue23.545.529.316.623.945.331.417.123.150.132.518.024.845.731.420.828.352.3
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:Residential0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

swx:SmallCommercial


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value568162354182693950897140558769415181
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax19.315.26.817.316.016.38.219.819.816.29.120.321.318.49.420.69.517.4
Percentage of RegulatedAndUnregulatedOperatingRevenue6.89.26.84.45.59.98.25.57.010.89.16.08.311.79.47.09.112.4
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SmallCommercial0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

swx:Transportation


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value212422211924242121242219202423202022
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax7.54.62.510.47.74.82.810.88.64.52.810.17.95.03.210.23.94.9
Percentage of RegulatedAndUnregulatedOperatingRevenue2.72.82.52.72.62.92.83.03.13.02.83.03.13.23.23.53.73.5
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:Transportation0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Revenues

us-gaap:Revenues

us-gaap:Revenues


Revenues
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value821885914791757836848725713833786668637727740564537633641512521709685505538734627432453608
Percentage of Revenues100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.095.196.4100.095.295.996.7100.095.095.397.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Revenues us-gaap:ConsolidationItems

us-gaap:MaterialReconcilingItems


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value2324237-32.0920.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Revenues2.92.725.9-4.10.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of RegulatedAndUnregulatedOperatingRevenue2.92.725.9-4.10.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:MaterialReconcilingItems0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:OperatingSegments


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value797861881759720803811690663794747631670754740593560654641539547731
Percentage of Revenues97.197.396.495.995.196.095.795.393.195.495.094.5105.2103.7100.0105.0104.3103.4100.0105.3104.9103.1
Percentage of RegulatedAndUnregulatedOperatingRevenue97.197.396.495.995.196.095.795.393.195.495.094.5100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:OperatingSegments0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:Revenues us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:MaterialReconcilingItems, swx:UtilityInfrastructureServicesSegment


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-30
Value2324237-32.0923633280-34.354
Percentage of Revenues2.92.725.9-4.14.94.033.1-4.7
Percentage of RegulatedAndUnregulatedOperatingRevenue2.92.725.9-4.14.94.033.1-4.7
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:MaterialReconcilingItems swx:UtilityInfrastructureServicesSegment0.00.00.00.00.00.00.00.0

us-gaap:OperatingSegments, swx:NaturalGasOperations


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value292521374210262502379209258520370217275494366213260462340200255525
Percentage of Revenues35.658.941.026.634.760.144.829.036.362.547.132.643.268.049.537.748.473.053.139.049.074.1
Percentage of RegulatedAndUnregulatedOperatingRevenue35.658.941.026.634.760.144.829.036.362.547.132.641.165.549.535.946.470.753.137.146.771.8
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:OperatingSegments swx:NaturalGasOperations0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:OperatingSegments, swx:UtilityInfrastructureServicesSegment


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value504339506548457300431480405274377414362232
Percentage of Revenues61.538.455.569.360.535.950.966.356.832.948.062.056.832.0
Percentage of RegulatedAndUnregulatedOperatingRevenue61.538.455.569.360.535.950.966.356.832.948.062.054.030.9
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:OperatingSegments swx:UtilityInfrastructureServicesSegment0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:Revenues us-gaap:StatementBusinessSegments

swx:NaturalGasOperations


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value292521374210262502379209258520370217275494366213260462340200255525
Percentage of Revenues35.658.941.026.634.760.144.829.036.362.547.132.643.268.049.537.748.473.053.139.049.074.1
Percentage of RegulatedAndUnregulatedOperatingRevenue35.658.941.026.634.760.144.829.036.362.547.132.641.165.549.535.946.470.753.137.146.771.8
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:NaturalGasOperations0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

swx:UtilityInfrastructureServicesSegment


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value528363539580494333468515454312416450395260
Percentage of Revenues64.441.159.073.465.339.955.271.063.737.552.967.462.035.8
Percentage of RegulatedAndUnregulatedOperatingRevenue64.441.159.073.465.339.955.271.063.737.552.967.458.934.5
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:UtilityInfrastructureServicesSegment0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Assets

us-gaap:Assets

us-gaap:Assets


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-312014-12-31
Value903989288735842984268093817078407666756973576654647663276237585556655551558153585208
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Assets dei:LegalEntity

swx:SouthwestGasCorporation


Assetsdei:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value7528751072566931697567686798645763246306614158115637558254825185503150065581
Percentage of Assets83.384.183.182.282.883.683.282.482.583.383.587.387.088.287.988.688.890.2100.0
Percentage of Assets83.384.183.182.282.883.683.282.482.583.383.587.387.088.287.988.688.890.2100.0
Percentage of Assets swx:SouthwestGasCorporation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Assets us-gaap:ConsolidationItems

us-gaap:MaterialReconcilingItems


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value3.986.1080.5721.9010.0
Percentage of Assets0.00.10.00.00.0
Percentage of Assets0.00.10.00.00.0
Percentage of Assets us-gaap:MaterialReconcilingItems100.0100.0100.0100.00.0

us-gaap:Assets us-gaap:StatementBusinessSegments

swx:NaturalGasOperations


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-31
Value7256679861415482500148224652
Percentage of Assets83.183.283.587.989.690.089.3
Percentage of Assets83.183.283.587.989.690.089.3
Percentage of Assets swx:NaturalGasOperations100.0100.0100.0100.0100.0100.0100.0

swx:UtilityInfrastructureServicesSegment


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value147513651215752579
Percentage of Assets16.916.716.512.110.4
Percentage of Assets16.916.716.512.110.4
Percentage of Assets swx:UtilityInfrastructureServicesSegment100.0100.0100.0100.0100.0

Liabilities And Stockholders Equity

us-gaap:LiabilitiesAndStockholdersEquity

us-gaap:LiabilitiesAndStockholdersEquity


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value90398928873584298426809381707840766675697357665464766327623758555665555155815358
Percentage of LiabilitiesAndStockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LiabilitiesAndStockholdersEquity dei:LegalEntity

swx:SouthwestGasCorporation


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value7528751072566931697567686798645763246306614158115637558254825185503150065581
Percentage of LiabilitiesAndStockholdersEquity83.384.183.182.282.883.683.282.482.583.383.587.387.088.287.988.688.890.2100.0
Percentage of Assets83.384.183.182.282.883.683.282.482.583.383.587.387.088.287.988.688.890.2100.0
Percentage of Assets swx:SouthwestGasCorporation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Stockholders Equity

us-gaap:StockholdersEquity

us-gaap:StockholdersEquity


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value28462773267426192611254725052423241923472252194619331879181417151716171516631594
Percentage of StockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets31.531.130.631.131.031.530.730.931.631.030.629.229.829.729.129.330.330.929.829.8

us-gaap:StockholdersEquity dei:LegalEntity

swx:SouthwestGasCorporation


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value2429237422332144215121142005192919481887178217191718167916091530154115501667
Percentage of StockholdersEquity85.385.683.581.982.483.080.079.680.580.479.188.488.989.388.789.289.890.4100.3
Percentage of Assets26.926.625.625.425.526.124.524.625.424.924.225.826.526.525.826.127.227.929.9
Percentage of Assets swx:SouthwestGasCorporation32.331.630.830.930.831.229.529.930.829.929.029.630.530.129.429.530.631.029.9

us-gaap:StockholdersEquity dei:LegalEntity, us-gaap:StatementEquityComponents

swx:SouthwestGasCorporation, us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-56.311-57.688-59.067-47.534-48.561-49.588-50.616-40.117-40.735-41.354-34.444-36.54-39.227
Percentage of StockholdersEquity-2.0-2.1-2.2-1.8-1.9-1.9-2.0-1.7-1.7-1.8-1.5-1.9-2.2
Percentage of Assets-0.6-0.6-0.7-0.6-0.6-0.6-0.6-0.5-0.5-0.5-0.5-0.5-0.6
Percentage of Assets swx:SouthwestGasCorporation us-gaap:AccumulatedDefinedBenefitPlansAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.0

swx:SouthwestGasCorporation, us-gaap:AccumulatedOtherComprehensiveIncome


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-57.552-59.343-61.135-50.015-51.825-53.487-55.151-45.287-46.54-47.795-49.049-51.779-47.073
Percentage of StockholdersEquity-2.0-2.1-2.3-1.9-2.0-2.1-2.2-1.9-1.9-2.0-2.2-2.7-2.6
Percentage of Assets-0.6-0.7-0.7-0.6-0.6-0.7-0.7-0.6-0.6-0.6-0.7-0.8-0.8
Percentage of Assets swx:SouthwestGasCorporation us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.0

swx:SouthwestGasCorporation, us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-1.241-1.655-2.068-2.481-3.264-3.899-4.535-5.17-5.805-6.441-5.305-5.939-7.846
Percentage of StockholdersEquity-0.0-0.1-0.1-0.1-0.1-0.2-0.2-0.2-0.2-0.3-0.2-0.3-0.4
Percentage of Assets-0.0-0.0-0.0-0.0-0.0-0.0-0.1-0.1-0.1-0.1-0.1-0.1-0.1
Percentage of Assets swx:SouthwestGasCorporation us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent0.00.00.00.00.00.00.00.00.00.00.00.00.0

Assets Current

us-gaap:AssetsCurrent

us-gaap:AssetsCurrent


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value10061000871732867672859765752830839721696663657538483454533558
Percentage of AssetsCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets11.111.210.08.710.38.310.59.89.811.011.410.810.710.510.59.28.58.29.610.4

us-gaap:AssetsCurrent dei:LegalEntity

swx:SouthwestGasCorporation


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value562632436274444372506374399533497402378430404279250302340
Percentage of AssetsCurrent55.963.150.137.551.255.458.948.953.164.359.255.854.464.961.551.951.866.663.8
Percentage of Assets6.27.15.03.35.34.66.24.85.27.16.86.15.96.86.54.84.45.46.1
Percentage of Assets swx:SouthwestGasCorporation7.58.46.04.06.45.57.45.86.38.58.16.96.77.77.45.45.06.06.1

Cash And Cash Equivalents At Carrying Value

us-gaap:CashAndCashEquivalentsAtCarryingValue

us-gaap:CashAndCashEquivalentsAtCarryingValue


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-31
Value479283231996049283897856934654359294328851260353248383941
Percentage of CashAndCashEquivalentsAtCarryingValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.51.01.00.32.40.80.60.40.51.31.21.00.51.00.71.00.50.80.50.00.00.00.70.00.00.00.80.0

us-gaap:CashAndCashEquivalentsAtCarryingValue dei:LegalEntity

swx:SouthwestGasCorporation


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-31
Value374941221905640163275314920453746223019785.627382118302514
Percentage of CashAndCashEquivalentsAtCarryingValue79.353.949.392.995.692.781.759.084.477.437.470.960.270.387.078.675.671.367.891.746.463.959.457.462.166.237.3
Percentage of Assets0.40.60.50.32.30.70.50.20.41.00.40.70.30.70.60.80.40.60.30.00.00.00.40.00.00.00.3
Percentage of Assets swx:SouthwestGasCorporation0.50.70.60.32.70.80.60.30.51.20.50.80.40.80.70.90.40.60.30.00.00.00.00.00.00.00.0

Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302015-12-31
Value479283231996049283897856934654359294328851235
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.51.01.00.32.40.80.60.40.51.31.21.00.51.00.71.00.50.80.50.00.00.7

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents dei:LegalEntity

swx:SouthwestGasCorporation


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302015-12-31
Value374941221905640163275314920453746223019785.62721
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents79.353.949.392.995.692.781.759.084.477.437.470.960.270.387.078.675.671.367.891.746.459.4
Percentage of Assets0.40.60.50.32.30.70.50.20.41.00.40.70.30.70.60.80.40.60.30.00.00.4
Percentage of Assets swx:SouthwestGasCorporation0.50.70.60.32.70.80.60.30.51.20.50.80.40.80.70.90.40.60.30.00.00.0

Accounts Receivable Net Current

us-gaap:AccountsReceivableNetCurrent

us-gaap:AccountsReceivableNetCurrent


Accounts
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value512479522513480423474434417429413347357335347301281247285314
Percentage of AccountsReceivableNetCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets5.75.46.06.15.75.25.85.55.45.75.65.25.55.35.65.25.04.55.15.9

us-gaap:AccountsReceivableNetCurrent dei:LegalEntity

swx:CenturiGroupInc.


Accounts
Period End2020-12-312019-12-31
Value375323
Percentage of AccountsReceivableNetCurrent71.968.2
Percentage of Assets4.34.0
Percentage of Assets swx:CenturiGroupInc.0.00.0

swx:SouthwestGasCorporation


Accounts
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value1181741468093148150739317014070831471196874118111
Percentage of AccountsReceivableNetCurrent23.236.428.115.719.535.231.816.922.439.733.820.223.444.034.522.526.448.139.2
Percentage of Assets1.32.01.71.01.11.81.80.91.22.31.91.11.32.31.91.21.32.12.0
Percentage of Assets swx:SouthwestGasCorporation1.62.32.01.21.32.22.21.11.52.72.31.21.52.72.21.31.52.42.0

Prepaid Expense And Other Assets Current

us-gaap:PrepaidExpenseAndOtherAssetsCurrent

us-gaap:PrepaidExpenseAndOtherAssetsCurrent


Prepaid
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value14913317015114713318019018717724322025018116513212610413695
Percentage of PrepaidExpenseAndOtherAssetsCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.71.51.91.81.81.62.22.42.42.33.33.33.92.92.72.32.21.92.51.8

us-gaap:PrepaidExpenseAndOtherAssetsCurrent dei:LegalEntity

swx:SouthwestGasCorporation


Prepaid
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value12011815213012311916517116716522920223317015311810894126
Percentage of PrepaidExpenseAndOtherAssetsCurrent80.788.789.886.083.989.491.589.989.593.094.292.093.094.193.089.786.490.992.3
Percentage of Assets1.31.31.71.51.51.52.02.22.22.23.13.03.62.72.52.01.91.72.3
Percentage of Assets swx:SouthwestGasCorporation1.61.62.11.91.81.82.42.72.72.63.73.54.13.12.82.32.21.92.3

Accumulated Depreciation Depletion And Amortization Property Plant And Equipment

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment dei:LegalEntity

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment

swx:CenturiGroupInc.


Accumulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value457439422406384363352345332316298
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets5.14.94.84.84.64.54.34.44.34.24.1
Percentage of Assets swx:CenturiGroupInc.0.00.00.00.00.00.00.00.00.00.00.0

Goodwill

us-gaap:Goodwill

us-gaap:Goodwill


Goodwill
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value348346345340337333343339345364359176174176179147143140139126
Percentage of Goodwill100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets3.93.94.04.04.04.14.24.34.54.84.92.62.72.82.92.52.52.52.52.4

us-gaap:Goodwill us-gaap:StatementBusinessSegments

swx:UtilityInfrastructureServicesSegment


Goodwillus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-312016-12-31
Value338336335330327323332329335354348169129
Percentage of Goodwill97.197.197.197.097.097.097.197.097.197.297.294.492.8
Percentage of Assets3.73.83.83.93.94.04.14.24.44.74.72.72.3
Percentage of Assets swx:UtilityInfrastructureServicesSegment0.00.022.70.00.00.024.40.00.00.028.722.522.4

Finite Lived Intangible Assets Net

us-gaap:FiniteLivedIntangibleAssetsNet dei:LegalEntity

us-gaap:FiniteLivedIntangibleAssetsNet

swx:CenturiGroupInc.


Finite
Period End2020-12-312019-12-312018-12-31
Value140150159
Percentage of FiniteLivedIntangibleAssetsNet100.0100.0100.0
Percentage of Assets1.61.82.2
Percentage of Assets swx:CenturiGroupInc.0.00.00.0

us-gaap:FiniteLivedIntangibleAssetsNet dei:LegalEntity, us-gaap:FiniteLivedIntangibleAssetsByMajorClass

swx:CenturiGroupInc., us-gaap:CustomerRelationships


Finite
Period End2020-12-312019-12-312018-12-31
Value125133140
Percentage of FiniteLivedIntangibleAssetsNet89.588.788.1
Percentage of Assets1.41.61.9
Percentage of Assets swx:CenturiGroupInc. us-gaap:CustomerRelationships0.00.00.0

swx:CenturiGroupInc., us-gaap:TrademarksAndTradeNames


Finite
Period End2020-12-312019-12-312018-12-31
Value141617
Percentage of FiniteLivedIntangibleAssetsNet10.511.011.1
Percentage of Assets0.20.20.2
Percentage of Assets swx:CenturiGroupInc. us-gaap:TrademarksAndTradeNames0.00.00.0

Operating Lease Right Of Use Asset

us-gaap:OperatingLeaseRightOfUseAsset dei:LegalEntity

us-gaap:OperatingLeaseRightOfUseAsset

swx:CenturiGroupInc.


Operating
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value8178716057
Percentage of OperatingLeaseRightOfUseAsset100.0100.0100.0100.0100.0
Percentage of Assets0.91.00.90.80.8
Percentage of Assets swx:CenturiGroupInc.0.00.00.00.00.0

swx:SouthwestGasCorporation


Operating
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value2.1951.4432.0082.0721.977
Percentage of OperatingLeaseRightOfUseAsset2.71.82.83.43.5
Percentage of Assets0.00.00.00.00.0
Percentage of Assets swx:SouthwestGasCorporation0.00.00.00.00.0

Other Assets Noncurrent

us-gaap:OtherAssetsNoncurrent

us-gaap:OtherAssetsNoncurrent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value488497508475474489496429436441440419425438447411416426432469
Percentage of OtherAssetsNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets5.45.65.85.65.66.06.15.55.75.86.06.36.66.97.27.07.37.77.78.8

us-gaap:OtherAssetsNoncurrent dei:LegalEntity

swx:SouthwestGasCorporation


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value471481490455454456463410417423424403410418425393399405410
Percentage of OtherAssetsNoncurrent96.696.896.495.995.793.393.295.595.796.096.496.196.595.595.195.796.095.095.0
Percentage of Assets5.25.45.65.45.45.65.75.25.45.65.86.16.36.66.86.77.17.37.4
Percentage of Assets swx:SouthwestGasCorporation6.36.46.86.66.56.76.86.46.66.76.96.97.37.57.87.67.98.17.4

Accounts Payable Current

us-gaap:AccountsPayableCurrent

us-gaap:AccountsPayableCurrent


Accounts
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value182182231175189182238188196231248172188175228159135134184164
Percentage of AccountsPayableCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets2.02.02.62.12.22.32.92.42.63.13.42.62.92.83.72.72.42.43.33.1

us-gaap:AccountsPayableCurrent dei:LegalEntity

swx:SouthwestGasCorporation


Accounts
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value9511716197911081499410614818498102117158928293138
Percentage of AccountsPayableCurrent52.564.369.955.548.359.662.549.854.264.174.357.554.567.069.457.960.869.674.9
Percentage of Assets1.11.31.91.21.11.31.81.21.42.02.51.51.61.92.51.61.51.72.5
Percentage of Assets swx:SouthwestGasCorporation1.31.62.21.41.31.62.21.51.72.43.01.71.82.12.91.81.61.92.5

Accrued Income Taxes Current

us-gaap:AccruedIncomeTaxesCurrent

us-gaap:AccruedIncomeTaxesCurrent


Accrued
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-31
Value1919121.0840.00.02.069
Percentage of AccruedIncomeTaxesCurrent100.0100.0100.0100.00.00.0100.0
Percentage of Assets0.20.20.10.00.00.00.0

us-gaap:AccruedIncomeTaxesCurrent dei:LegalEntity

swx:SouthwestGasCorporation


Accrued
Period End2021-03-312020-06-302020-03-312019-12-31
Value7.2328.538190.0
Percentage of AccruedIncomeTaxesCurrent37.40.00.00.0
Percentage of Assets0.10.10.20.0
Percentage of Assets swx:SouthwestGasCorporation0.10.10.30.0

Contract With Customer Liability Current

us-gaap:ContractWithCustomerLiabilityCurrent

us-gaap:ContractWithCustomerLiabilityCurrent


Contract
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-31
Value44676769696969
Percentage of ContractWithCustomerLiabilityCurrent100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.50.80.80.80.80.90.8

us-gaap:ContractWithCustomerLiabilityCurrent dei:LegalEntity

swx:SouthwestGasCorporation


Contract
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-31
Value44676769696969
Percentage of ContractWithCustomerLiabilityCurrent100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.50.80.80.80.80.90.8
Percentage of Assets swx:SouthwestGasCorporation0.60.90.91.01.01.01.0

Dividends Payable Current

us-gaap:DividendsPayableCurrent

us-gaap:DividendsPayableCurrent


Dividends
Period End2021-06-302021-03-312020-12-312019-12-31
Value35343230
Percentage of DividendsPayableCurrent100.0100.0100.0100.0
Percentage of Assets0.40.40.40.4

us-gaap:DividendsPayableCurrent dei:LegalEntity

swx:SouthwestGasCorporation


Dividends
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302018-12-31
Value27262525242423
Percentage of DividendsPayableCurrent0.00.00.084.00.00.00.0
Percentage of Assets0.30.30.30.30.30.30.3
Percentage of Assets swx:SouthwestGasCorporation0.40.40.40.40.40.40.4

Liabilities Current

us-gaap:LiabilitiesCurrent

us-gaap:LiabilitiesCurrent


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value127210369118399189791079782726974938712663602815656490496628535
Percentage of LiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets14.111.610.410.010.912.113.210.09.512.912.810.710.29.513.111.28.68.911.310.0

us-gaap:LiabilitiesCurrent dei:LegalEntity

swx:SouthwestGasCorporation


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value923731556475574702795483441678643463423411601446332376482
Percentage of LiabilitiesCurrent72.670.661.056.762.571.773.661.860.769.668.565.063.968.373.768.067.975.776.8
Percentage of Assets10.28.26.45.66.88.79.76.25.89.08.77.06.56.59.67.65.96.88.6
Percentage of Assets swx:SouthwestGasCorporation12.39.77.76.98.210.411.77.57.010.810.58.07.57.411.08.66.67.58.6

Long Term Debt Current

us-gaap:LongTermDebtCurrent

us-gaap:LongTermDebtCurrent


Long
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value31967404417116916338363433333124252827265019
Percentage of LongTermDebtCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets3.50.80.50.52.02.12.00.50.50.50.40.50.50.40.40.50.50.50.90.4

us-gaap:LongTermDebtCurrent dei:LegalEntity

swx:SouthwestGasCorporation


Long
Period End2021-06-302021-03-312020-06-302020-03-312019-12-312018-12-312016-12-31
Value275251251251250.025
Percentage of LongTermDebtCurrent86.137.172.873.776.40.049.9
Percentage of Assets3.00.31.51.51.50.00.4
Percentage of Assets swx:SouthwestGasCorporation3.70.31.81.81.80.00.4

us-gaap:LongTermDebtCurrent dei:LegalEntity, us-gaap:FairValueByMeasurementBasis

swx:CenturiGroupInc., us-gaap:CarryingReportedAmountFairValueDisclosure


Long
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value4442404446443838363433
Percentage of LongTermDebtCurrent13.962.9100.0100.027.226.323.6100.0100.0100.0100.0
Percentage of Assets0.50.50.50.50.60.60.50.50.50.50.4
Percentage of Assets swx:CenturiGroupInc. us-gaap:CarryingReportedAmountFairValueDisclosure0.00.00.00.00.00.00.00.00.00.00.0

swx:SouthwestGasCorporation, us-gaap:CarryingReportedAmountFairValueDisclosure


Long
Period End2021-06-302021-03-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-312016-12-31
Value275251251251250.00.00.00.00.025
Percentage of LongTermDebtCurrent86.137.172.873.776.40.00.00.00.00.049.9
Percentage of Assets3.00.31.51.51.50.00.00.00.00.00.4
Percentage of Assets swx:SouthwestGasCorporation us-gaap:CarryingReportedAmountFairValueDisclosure0.00.00.00.00.00.00.00.00.00.00.0

us-gaap:LongTermDebtCurrent dei:LegalEntity, us-gaap:LongtermDebtType

swx:SouthwestGasCorporation, swx:SouthwestGasCreditFacility


Long
Period End2021-06-302021-03-31
Value4117
Percentage of LongTermDebtCurrent12.825.2
Percentage of Assets0.50.2
Percentage of Assets swx:SouthwestGasCorporation swx:SouthwestGasCreditFacility0.00.0

us-gaap:LongTermDebtCurrent us-gaap:FairValueByMeasurementBasis

us-gaap:CarryingReportedAmountFairValueDisclosure


Long
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312018-12-312018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value319674044171169163333124252827265019
Percentage of LongTermDebtCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets3.50.80.50.52.02.12.00.40.50.40.40.50.50.50.90.4
Percentage of Assets us-gaap:CarryingReportedAmountFairValueDisclosure0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Operating Lease Liability Current

us-gaap:OperatingLeaseLiabilityCurrent dei:LegalEntity

us-gaap:OperatingLeaseLiabilityCurrent

swx:CenturiGroupInc.


Operating
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value108.8518.1837.9657.178
Percentage of OperatingLeaseLiabilityCurrent100.0100.0100.0100.0100.0
Percentage of Assets0.10.10.10.10.1
Percentage of Assets swx:CenturiGroupInc.0.00.00.00.00.0

swx:SouthwestGasCorporation


Operating
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value0.6560.7230.8260.8970.745
Percentage of OperatingLeaseLiabilityCurrent6.58.210.111.310.4
Percentage of Assets0.00.00.00.00.0
Percentage of Assets swx:SouthwestGasCorporation0.00.00.00.00.0

Other Liabilities Current

us-gaap:OtherLiabilitiesCurrent

us-gaap:OtherLiabilitiesCurrent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value317282328322289266264279269278290229262208203197175149168150
Percentage of OtherLiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets3.53.23.83.83.43.33.23.63.53.74.03.44.03.33.33.43.12.73.02.8

us-gaap:OtherLiabilitiesCurrent dei:LegalEntity

swx:SouthwestGasCorporation


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value14514114613713914712611411010094111162122108109987395
Percentage of OtherLiabilitiesCurrent45.949.944.442.748.155.547.841.041.136.132.448.661.958.853.555.456.449.257.1
Percentage of Assets1.61.61.71.61.71.81.51.51.41.31.31.72.51.91.71.91.71.31.7
Percentage of Assets swx:SouthwestGasCorporation1.91.92.02.02.02.21.91.81.81.61.51.92.92.22.02.12.01.51.7

Long Term Debt

us-gaap:LongTermDebt dei:LegalEntity, us-gaap:CreditFacility

us-gaap:LongTermDebt

swx:SouthwestGasCorporation, swx:A400MillionCreditFacility


Long
Period End2020-09-302020-06-302020-03-312019-09-30
Value580.0150150
Percentage of LongTermDebt100.00.0100.0100.0
Percentage of Assets0.70.01.91.9
Percentage of Assets swx:SouthwestGasCorporation swx:A400MillionCreditFacility0.00.00.00.0

us-gaap:LongTermDebt dei:LegalEntity, us-gaap:FairValueByMeasurementBasis

swx:CenturiGroupInc., us-gaap:CarryingReportedAmountFairValueDisclosure


Long
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value359325334384398363347384398322321
Percentage of LongTermDebt0.00.00.0663.40.0242.00.0256.30.00.00.0
Percentage of Assets4.03.63.84.64.74.54.34.95.24.34.4
Percentage of Assets swx:CenturiGroupInc. us-gaap:CarryingReportedAmountFairValueDisclosure0.00.00.00.00.00.00.00.00.00.00.0

swx:SouthwestGasCorporation, us-gaap:CarryingReportedAmountFairValueDisclosure


Long
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302016-12-31
Value243824382438234524122116211621152011181818181818171617061521152014621400
Percentage of LongTermDebt0.00.00.04044.60.01411.10.01410.60.00.00.00.00.00.00.00.00.00.0
Percentage of Assets27.027.327.927.828.626.225.927.026.224.024.727.326.527.024.426.025.825.1
Percentage of Assets swx:SouthwestGasCorporation us-gaap:CarryingReportedAmountFairValueDisclosure0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:LongTermDebt dei:LegalEntity, us-gaap:LongtermDebtType

swx:SouthwestGasCorporation, swx:SouthwestGasCreditFacility


Long
Period End2021-06-302021-03-312020-12-312019-12-312019-06-302019-03-312018-12-312018-09-30
Value15015015015046150150150
Percentage of LongTermDebt0.00.00.00.00.00.00.00.0
Percentage of Assets1.71.71.71.80.62.02.02.3
Percentage of Assets swx:SouthwestGasCorporation swx:SouthwestGasCreditFacility0.00.00.00.00.00.00.00.0

Long Term Debt Noncurrent

us-gaap:LongTermDebtNoncurrent

us-gaap:LongTermDebtNoncurrent


Long
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value24782696273226852639231023002462237321062107212320371998179817311685156415491551
Percentage of LongTermDebtNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets27.430.231.331.931.328.528.231.431.027.828.631.931.531.628.829.629.828.227.828.9

us-gaap:LongTermDebtNoncurrent dei:LegalEntity

swx:SouthwestGasCorporation


Long
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value2163241324382345228719911991211520111818181818181716170615211520146213851375
Percentage of LongTermDebtNoncurrent87.389.589.287.386.786.286.685.984.886.486.385.684.285.484.687.886.888.688.7
Percentage of Assets23.927.027.927.827.124.624.427.026.224.024.727.326.527.024.426.025.825.024.6
Percentage of Assets swx:SouthwestGasCorporation28.732.133.633.832.829.429.332.831.828.829.631.330.430.627.729.329.127.724.6

us-gaap:LongTermDebtNoncurrent dei:LegalEntity, us-gaap:FairValueByMeasurementBasis

swx:CenturiGroupInc., us-gaap:CarryingReportedAmountFairValueDisclosure


Long
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value314282293339351318309346361287288
Percentage of LongTermDebtNoncurrent12.710.510.812.713.313.813.414.115.213.613.7
Percentage of Assets3.53.23.44.04.23.93.84.44.73.83.9
Percentage of Assets swx:CenturiGroupInc. us-gaap:CarryingReportedAmountFairValueDisclosure0.00.00.00.00.00.00.00.00.00.00.0

swx:SouthwestGasCorporation, us-gaap:CarryingReportedAmountFairValueDisclosure


Long
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value2163241324382345228719911991211520111818181818181716170615211520146213851375
Percentage of LongTermDebtNoncurrent87.389.589.287.386.786.286.685.984.886.486.385.684.285.484.687.886.888.688.7
Percentage of Assets23.927.027.927.827.124.624.427.026.224.024.727.326.527.024.426.025.825.024.6
Percentage of Assets swx:SouthwestGasCorporation us-gaap:CarryingReportedAmountFairValueDisclosure0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:LongTermDebtNoncurrent us-gaap:FairValueByMeasurementBasis

us-gaap:CarryingReportedAmountFairValueDisclosure


Long
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value24782696273226852639231023002462237321062107212320371998179817311685156415491551
Percentage of LongTermDebtNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets27.430.231.331.931.328.528.231.431.027.828.631.931.531.628.829.629.828.227.828.9
Percentage of Assets us-gaap:CarryingReportedAmountFairValueDisclosure0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Other Liabilities Noncurrent

us-gaap:OtherLiabilitiesNoncurrent

us-gaap:OtherLiabilitiesNoncurrent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value22402217225121782170217021992087206420591978187218421850181017531755175417181664
Percentage of OtherLiabilitiesNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets24.824.825.825.825.826.826.926.626.927.226.928.128.429.229.029.931.031.630.831.1

us-gaap:OtherLiabilitiesNoncurrent dei:LegalEntity

swx:SouthwestGasCorporation


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value2011199120281965196219602007192919231921189718091777178417501688169416942039
Percentage of OtherLiabilitiesNoncurrent89.889.890.190.290.490.391.392.493.293.395.996.696.596.496.796.396.596.6118.7
Percentage of Assets22.322.323.223.323.324.224.624.625.125.425.827.227.528.228.128.829.930.536.5
Percentage of Assets swx:SouthwestGasCorporation26.726.528.028.428.129.029.529.930.430.530.931.131.532.031.932.633.733.936.5

Operating Lease Liability Noncurrent

us-gaap:OperatingLeaseLiabilityNoncurrent dei:LegalEntity

us-gaap:OperatingLeaseLiabilityNoncurrent

swx:CenturiGroupInc.


Operating
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value7573655552
Percentage of OperatingLeaseLiabilityNoncurrent100.0100.0100.0100.0100.0
Percentage of Assets0.90.90.80.70.7
Percentage of Assets swx:CenturiGroupInc.0.00.00.00.00.0

swx:SouthwestGasCorporation


Operating
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value1.5860.731.2091.21.253
Percentage of OperatingLeaseLiabilityNoncurrent2.11.01.82.22.4
Percentage of Assets0.00.00.00.00.0
Percentage of Assets swx:SouthwestGasCorporation0.00.00.00.00.0

Lessee Operating Lease Liability Payments Due Year Two

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo dei:LegalEntity

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo

swx:CenturiGroupInc.


Lessee
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value1211109.5519.327
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearTwo100.0100.0100.0100.0100.0
Percentage of Assets0.10.10.10.10.1
Percentage of Assets swx:CenturiGroupInc.0.00.00.00.00.0

swx:SouthwestGasCorporation


Lessee
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value0.5430.3760.5480.5340.556
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearTwo4.53.35.35.66.0
Percentage of Assets0.00.00.00.00.0
Percentage of Assets swx:SouthwestGasCorporation0.00.00.00.00.0

Lessee Operating Lease Liability Payments Due Year Three

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree dei:LegalEntity

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree

swx:CenturiGroupInc.


Lessee
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value10109.6758.7368.328
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearThree100.0100.0100.0100.0100.0
Percentage of Assets0.10.10.10.10.1
Percentage of Assets swx:CenturiGroupInc.0.00.00.00.00.0

swx:SouthwestGasCorporation


Lessee
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value0.4260.1880.2440.2130.295
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearThree3.91.82.52.43.5
Percentage of Assets0.00.00.00.00.0
Percentage of Assets swx:SouthwestGasCorporation0.00.00.00.00.0

Lessee Operating Lease Liability Payments Due Year Four

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour dei:LegalEntity

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour

swx:CenturiGroupInc.


Lessee
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value9904000.08823000.08192000.07548000.07645000.0
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFour100.0100.0100.0100.0100.0
Percentage of Assets0.10.10.10.10.1
Percentage of Assets swx:CenturiGroupInc.0.00.00.00.00.0

swx:SouthwestGasCorporation


Lessee
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value404000.078000.079000.0102000.0124000.0
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFour4.10.91.01.41.6
Percentage of Assets0.00.00.00.00.0
Percentage of Assets swx:SouthwestGasCorporation0.00.00.00.00.0

Lessee Operating Lease Liability Payments Due Year Five

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive dei:LegalEntity

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive

swx:CenturiGroupInc.


Lessee
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value8051000.08065000.06973000.05992000.05710000.0
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFive100.0100.0100.0100.0100.0
Percentage of Assets0.10.10.10.10.1
Percentage of Assets swx:CenturiGroupInc.0.00.00.00.00.0

swx:SouthwestGasCorporation


Lessee
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value330000.056000.079000.078000.078000.0
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFive4.10.71.11.31.4
Percentage of Assets0.00.00.00.00.0
Percentage of Assets swx:SouthwestGasCorporation0.00.00.00.00.0

Lessee Operating Lease Liability Payments Due After Year Five

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive dei:LegalEntity

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive

swx:CenturiGroupInc.


Lessee
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value5049453431
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive100.0100.0100.0100.0100.0
Percentage of Assets0.60.60.60.40.4
Percentage of Assets swx:CenturiGroupInc.0.00.00.00.00.0

swx:SouthwestGasCorporation


Lessee
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value0.0360.0740.2670.2870.307
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive0.10.10.60.81.0
Percentage of Assets0.00.00.00.00.0
Percentage of Assets swx:SouthwestGasCorporation0.00.00.00.00.0

Operating Lease Liability

us-gaap:OperatingLeaseLiability dei:LegalEntity

us-gaap:OperatingLeaseLiability

swx:CenturiGroupInc.


Operating
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value8582736359
Percentage of OperatingLeaseLiability100.0100.0100.0100.0100.0
Percentage of Assets1.01.00.90.80.8
Percentage of Assets swx:CenturiGroupInc.0.00.00.00.00.0

swx:SouthwestGasCorporation


Operating
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value2.2421.4532.0352.0971.998
Percentage of OperatingLeaseLiability2.61.82.83.33.3
Percentage of Assets0.00.00.00.00.0
Percentage of Assets swx:SouthwestGasCorporation0.00.00.00.00.0

Lessee Operating Lease Liability Payments Due

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue dei:LegalEntity

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue

swx:CenturiGroupInc.


Lessee
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value104100927672
Percentage of LesseeOperatingLeaseLiabilityPaymentsDue100.0100.0100.0100.0100.0
Percentage of Assets1.21.21.21.01.0
Percentage of Assets swx:CenturiGroupInc.0.00.00.00.00.0

swx:SouthwestGasCorporation


Lessee
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value2.4741.5282.1632.2322.16
Percentage of LesseeOperatingLeaseLiabilityPaymentsDue2.41.52.32.93.0
Percentage of Assets0.00.00.00.00.0
Percentage of Assets swx:SouthwestGasCorporation0.00.00.00.00.0

Lessee Operating Lease Liability Undiscounted Excess Amount

us-gaap:LesseeOperatingLeaseLiabilityUndiscountedExcessAmount dei:LegalEntity

us-gaap:LesseeOperatingLeaseLiabilityUndiscountedExcessAmount

swx:CenturiGroupInc.


Lessee
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value1918181312
Percentage of LesseeOperatingLeaseLiabilityUndiscountedExcessAmount100.0100.0100.0100.0100.0
Percentage of Assets0.20.20.20.20.2
Percentage of Assets swx:CenturiGroupInc.0.00.00.00.00.0

swx:SouthwestGasCorporation


Lessee
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value0.2320.0750.1280.1350.162
Percentage of LesseeOperatingLeaseLiabilityUndiscountedExcessAmount1.20.40.71.01.3
Percentage of Assets0.00.00.00.00.0
Percentage of Assets swx:SouthwestGasCorporation0.00.00.00.00.0

Stockholders Equity

us-gaap:StockholdersEquity

us-gaap:StockholdersEquity


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value28462773267426192611254725052423241923472252194619331879181417151716171516631594
Percentage of StockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets31.531.130.631.131.031.530.730.931.631.030.629.229.829.729.129.330.330.929.829.8

us-gaap:StockholdersEquity dei:LegalEntity

swx:SouthwestGasCorporation


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value2429237422332144215121142005192919481887178217191718167916091530154115501667
Percentage of StockholdersEquity85.385.683.581.982.483.080.079.680.580.479.188.488.989.388.789.289.890.4100.3
Percentage of Assets26.926.625.625.425.526.124.524.625.424.924.225.826.526.525.826.127.227.929.9
Percentage of Assets swx:SouthwestGasCorporation32.331.630.830.930.831.229.529.930.829.929.029.630.530.129.429.530.631.029.9

us-gaap:StockholdersEquity dei:LegalEntity, us-gaap:StatementEquityComponents

swx:SouthwestGasCorporation, us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-56.311-57.688-59.067-47.534-48.561-49.588-50.616-40.117-40.735-41.354-34.444-36.54-39.227
Percentage of StockholdersEquity-2.0-2.1-2.2-1.8-1.9-1.9-2.0-1.7-1.7-1.8-1.5-1.9-2.2
Percentage of Assets-0.6-0.6-0.7-0.6-0.6-0.6-0.6-0.5-0.5-0.5-0.5-0.5-0.6
Percentage of Assets swx:SouthwestGasCorporation us-gaap:AccumulatedDefinedBenefitPlansAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.0

swx:SouthwestGasCorporation, us-gaap:AccumulatedOtherComprehensiveIncome


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-57.552-59.343-61.135-50.015-51.825-53.487-55.151-45.287-46.54-47.795-49.049-51.779-47.073
Percentage of StockholdersEquity-2.0-2.1-2.3-1.9-2.0-2.1-2.2-1.9-1.9-2.0-2.2-2.7-2.6
Percentage of Assets-0.6-0.7-0.7-0.6-0.6-0.7-0.7-0.6-0.6-0.6-0.7-0.8-0.8
Percentage of Assets swx:SouthwestGasCorporation us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.0

swx:SouthwestGasCorporation, us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-1.241-1.655-2.068-2.481-3.264-3.899-4.535-5.17-5.805-6.441-5.305-5.939-7.846
Percentage of StockholdersEquity-0.0-0.1-0.1-0.1-0.1-0.2-0.2-0.2-0.2-0.3-0.2-0.3-0.4
Percentage of Assets-0.0-0.0-0.0-0.0-0.0-0.0-0.1-0.1-0.1-0.1-0.1-0.1-0.1
Percentage of Assets swx:SouthwestGasCorporation us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent0.00.00.00.00.00.00.00.00.00.00.00.00.0

Stockholders Equity Including Portion Attributable To Noncontrolling Interest

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest


Stockholders
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-312014-12-312013-12-31
Value26742619261125472505242324192346225119451932187618121713171417131661159214861412
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets30.631.131.031.530.730.931.631.030.629.229.829.729.129.330.330.929.829.728.50.0

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest dei:LegalEntity

swx:SouthwestGasCorporation


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value24292374223321442151211420051929194818871782171917181679160915301541155016671593
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest0.00.083.581.982.483.080.079.680.580.579.288.488.989.588.889.389.990.5100.4100.1
Percentage of Assets26.926.625.625.425.526.124.524.625.424.924.225.826.526.525.826.127.227.929.929.7
Percentage of Assets swx:SouthwestGasCorporation32.331.630.830.930.831.229.529.930.829.929.029.630.530.129.429.530.631.029.90.0

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest dei:LegalEntity, us-gaap:StatementEquityComponents

swx:SouthwestGasCorporation, us-gaap:AccumulatedOtherComprehensiveIncome


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value-57.552-59.343-61.135-50.015-51.825-53.487-55.151-45.287-46.54-47.795-49.049-51.779-53.31-54.843-47.073-42.299-43.413-44.526-45.639-47.743
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest0.00.0-2.3-1.9-2.0-2.1-2.2-1.9-1.9-2.0-2.2-2.7-2.8-2.9-2.6-2.5-2.5-2.6-2.7-3.0
Percentage of Assets-0.6-0.7-0.7-0.6-0.6-0.7-0.7-0.6-0.6-0.6-0.7-0.8-0.8-0.9-0.8-0.7-0.8-0.8-0.8-0.9
Percentage of Assets swx:SouthwestGasCorporation us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

swx:SouthwestGasCorporation, us-gaap:AdditionalPaidInCapital


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value1529145814101363132912791229119411691089106510411006948948917904903897890
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest0.00.052.752.150.950.249.049.348.346.447.353.552.150.552.353.652.852.754.055.9
Percentage of Assets16.916.316.116.215.815.815.015.215.314.414.515.615.515.015.215.716.016.316.116.6
Percentage of Assets swx:SouthwestGasCorporation us-gaap:AdditionalPaidInCapital0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

swx:SouthwestGasCorporation, us-gaap:CommonStock


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value4949494949494949494949494949494949494949
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest0.00.01.81.91.91.92.02.02.02.12.22.52.52.62.72.92.92.93.03.1
Percentage of Assets0.50.60.60.60.60.60.60.60.60.60.70.70.80.80.80.80.90.90.90.9
Percentage of Assets swx:SouthwestGasCorporation us-gaap:CommonStock0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

swx:SouthwestGasCorporation, us-gaap:RetainedEarnings


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value908926835781824839782731776797717681717736659606631642767701
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest0.00.031.229.831.632.931.230.232.134.031.935.037.139.336.435.436.837.546.244.0
Percentage of Assets10.110.49.69.39.810.49.69.310.110.59.710.211.111.610.610.411.111.613.713.1
Percentage of Assets swx:SouthwestGasCorporation us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest us-gaap:StatementEquityComponents

us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-56.311-57.688-59.067-47.534-48.561-49.588-50.616-40.117-40.735-41.354-34.444-36.54-39.227
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest0.00.0-2.2-1.8-1.9-1.9-2.0-1.7-1.7-1.8-1.5-1.9-2.2
Percentage of Assets-0.6-0.6-0.7-0.6-0.6-0.6-0.6-0.5-0.5-0.5-0.5-0.5-0.6
Percentage of Assets us-gaap:AccumulatedDefinedBenefitPlansAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterest


Stockholders
Period End2021-06-302021-03-312020-12-312019-12-312018-12-312017-12-31
Value1.8640.9550.132-1.581-3.619-0.609
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest0.00.00.0-0.1-0.2-0.0
Percentage of Assets0.00.00.0-0.0-0.0-0.0
Percentage of Assets us-gaap:AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterest0.00.00.00.00.00.0

us-gaap:AccumulatedOtherComprehensiveIncome


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-312014-12-312013-12-31
Value-55.688-58.388-61.003-52.783-55.617-59.073-56.732-47.775-48.581-50.623-52.668-53.39-55.52-56.363-47.682-42.818-44.962-46.682-48.008-50.268-50.175-41.698
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest0.00.0-2.3-2.0-2.1-2.3-2.3-2.0-2.0-2.2-2.3-2.7-2.9-3.0-2.6-2.5-2.6-2.7-2.9-3.2-3.4-3.0
Percentage of Assets-0.6-0.7-0.7-0.6-0.7-0.7-0.7-0.6-0.6-0.7-0.7-0.8-0.9-0.9-0.8-0.7-0.8-0.8-0.9-0.9-1.00.0
Percentage of Assets us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedTranslationAdjustment


Stockholders
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-2.768-3.792-5.586-1.581-2.488-2.041-2.828-3.619-1.611-0.609
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest-0.1-0.1-0.2-0.1-0.1-0.1-0.1-0.2-0.1-0.0
Percentage of Assets-0.0-0.0-0.1-0.0-0.0-0.0-0.0-0.0-0.0-0.0
Percentage of Assets us-gaap:AccumulatedTranslationAdjustment0.00.00.00.00.00.00.00.00.00.0

us-gaap:AdditionalPaidInCapital


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-312014-12-312013-12-31
Value1733166016091559152314701466143714091332130510451021965955924911909903896851840
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest0.00.060.259.658.357.758.559.358.356.858.053.752.951.552.753.953.153.154.456.357.359.5
Percentage of Assets19.218.618.418.518.118.218.018.318.417.617.715.715.815.315.315.816.116.416.216.716.30.0
Percentage of Assets us-gaap:AdditionalPaidInCapital0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-1.241-1.655-2.068-2.481-3.264-3.899-4.535-5.17-5.805-6.441-5.305-5.939-7.846
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest0.00.0-0.1-0.1-0.1-0.2-0.2-0.2-0.2-0.3-0.2-0.3-0.4
Percentage of Assets-0.0-0.0-0.0-0.0-0.0-0.0-0.1-0.1-0.1-0.1-0.1-0.1-0.1
Percentage of Assets us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent0.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:CommonStock


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-312014-12-312013-12-31
Value60595858575656565555545150494949494949494847
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest0.00.02.22.22.22.22.32.32.32.32.42.62.62.72.72.92.92.93.03.13.23.4
Percentage of Assets0.70.70.70.70.70.70.70.70.70.70.70.80.80.80.80.80.90.90.90.90.90.0
Percentage of Assets us-gaap:CommonStock0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:Parent


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value28462773267426192611254725052423241923472252194619331814
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest0.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.1
Percentage of Assets31.531.130.631.131.031.530.730.931.631.030.629.229.829.1
Percentage of Assets us-gaap:Parent0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:RetainedEarnings


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-312014-12-312013-12-31
Value110811121067105410851079103997710021009944902916920857784801803759699639567
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest0.00.039.940.241.642.441.540.341.443.041.946.447.449.147.345.846.746.945.743.943.040.2
Percentage of Assets12.312.512.212.512.913.312.712.513.113.312.813.614.114.513.713.414.114.513.613.012.30.0
Percentage of Assets us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Common Stock Value

us-gaap:CommonStockValue

us-gaap:CommonStockValue


Common
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value6059585857565656555554515049494949494949
Percentage of CommonStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.70.70.70.70.70.70.70.70.70.70.70.80.80.80.80.80.90.90.90.9

Additional Paid In Capital Common Stock

us-gaap:AdditionalPaidInCapitalCommonStock

us-gaap:AdditionalPaidInCapitalCommonStock


Additional
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value1733166016091559152314701466143714091332130510451021965955924911909903896
Percentage of AdditionalPaidInCapitalCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets19.218.618.418.518.118.218.018.318.417.617.715.715.815.315.315.816.116.416.216.7

us-gaap:AdditionalPaidInCapitalCommonStock dei:LegalEntity

swx:SouthwestGasCorporation


Additional
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value1529145814101363132912791229119411691089106510411006948948917904903897
Percentage of AdditionalPaidInCapitalCommonStock88.287.887.687.487.387.083.883.183.081.781.699.698.598.299.399.399.399.399.4
Percentage of Assets16.916.316.116.215.815.815.015.215.314.414.515.615.515.015.215.716.016.316.1
Percentage of Assets swx:SouthwestGasCorporation20.319.419.419.719.118.918.118.518.517.317.317.917.817.017.317.718.018.016.1

Retained Earnings Accumulated Deficit

us-gaap:RetainedEarningsAccumulatedDeficit

us-gaap:RetainedEarningsAccumulatedDeficit


Retained
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value110811121067105410851079103997710021009944902916920857784801803759699
Percentage of RetainedEarningsAccumulatedDeficit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets12.312.512.212.512.913.312.712.513.113.312.813.614.114.513.713.414.114.513.613.0

us-gaap:RetainedEarningsAccumulatedDeficit dei:LegalEntity

swx:SouthwestGasCorporation


Retained
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value908926835781824839782731776797717681717736659606631642767
Percentage of RetainedEarningsAccumulatedDeficit82.083.278.274.276.077.775.374.877.479.075.975.578.380.076.977.278.880.0101.0
Percentage of Assets10.110.49.69.39.810.49.69.310.110.59.710.211.111.610.610.411.111.613.7
Percentage of Assets swx:SouthwestGasCorporation12.112.311.511.311.812.411.511.312.312.611.711.712.713.212.011.712.512.813.7

Accumulated Other Comprehensive Income Loss Net Of Tax

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax


Accumulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value-55688000.0-58388000.0-61003000.0-52783000.0-55617000.0-59073000.0-56732000.0-47775000.0-48581000.0-50623000.0-52668000.0-53390000.0-55520000.0-56363000.0-47682000.0-42818000.0-44962000.0-46682000.0-48008000.0-50268000.0
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets-0.6-0.7-0.7-0.6-0.7-0.7-0.7-0.6-0.6-0.7-0.7-0.8-0.9-0.9-0.8-0.7-0.8-0.8-0.9-0.9

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax dei:LegalEntity

swx:SouthwestGasCorporation


Accumulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value-57552000.0-59343000.0-61135000.0-50015000.0-51825000.0-53487000.0-55151000.0-45287000.0-46540000.0-47795000.0-49049000.0-51779000.0-53310000.0-54843000.0-47073000.0-42299000.0-43413000.0-44526000.0-45639000.0
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax103.3101.6100.294.893.290.597.294.895.894.493.197.096.097.398.798.896.695.495.1
Percentage of Assets-0.6-0.7-0.7-0.6-0.6-0.7-0.7-0.6-0.6-0.6-0.7-0.8-0.8-0.9-0.8-0.7-0.8-0.8-0.8
Percentage of Assets swx:SouthwestGasCorporation-0.8-0.8-0.8-0.7-0.7-0.8-0.8-0.7-0.7-0.8-0.8-0.9-0.9-1.0-0.9-0.8-0.9-0.9-0.8

Stock Issued During Period Value New Issues

us-gaap:StockIssuedDuringPeriodValueNewIssues us-gaap:PlanName

us-gaap:StockIssuedDuringPeriodValueNewIssues

swx:DividendReinvestmentAndStockPurchasePlan


Stock
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value2.73.12.03.02.93.13.92.62.72.8
Percentage of StockIssuedDuringPeriodValueNewIssues100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.0
Percentage of Assets swx:DividendReinvestmentAndStockPurchasePlan0.00.00.00.00.00.00.00.00.00.0

us-gaap:StockIssuedDuringPeriodValueNewIssues us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital


Stock
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value73504936533.4742927772725924561031131.7336.239
Percentage of StockIssuedDuringPeriodValueNewIssues2720.91643.62467.11206.11835.1112.1748.81069.62873.4965.10.00.00.00.00.00.00.00.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets us-gaap:AdditionalPaidInCapital0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:CommonStock


Stock
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value1.0930.8020.7340.5490.7840.1190.3830.3030.930.3653.6030.2970.7890.2470.3580.1490.0340.067
Percentage of StockIssuedDuringPeriodValueNewIssues40.525.936.718.327.03.89.811.734.413.00.00.00.00.00.00.00.00.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets us-gaap:CommonStock0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInOperatingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value53-52.457138112103271121100901881211606618070101
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue6.6-5.915.114.213.732.514.413.812.722.615.424.09.923.99.517.0

us-gaap:NetCashProvidedByUsedInOperatingActivities dei:LegalEntity

swx:SouthwestGasCorporation


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value66-95.4321159942593867911703510180164
Percentage of NetCashProvidedByUsedInOperatingActivities122.7181.98.052.891.395.431.467.6101.390.628.863.5121.491.3
Percentage of RegulatedAndUnregulatedOperatingRevenue8.0-10.81.27.512.531.04.59.312.820.44.515.312.021.9
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation0.00.02.928.236.051.510.132.235.432.79.546.829.333.4

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-176520000.0-144860000.0-183560000.0-203970000.0-213750000.0-200790000.0-240620000.0-230540000.0-273150000.0-207320000.0-449990000.0-217000000.0-178290000.0-154210000.0-258100000.0-186030000.0
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue-21.5-16.4-20.1-25.8-28.2-24.0-28.4-31.8-38.3-24.9-57.2-32.5-26.6-20.4-34.9-31.4

us-gaap:NetCashProvidedByUsedInInvestingActivities dei:LegalEntity

swx:SouthwestGasCorporation


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-144220000.0-124380000.0-160060000.0-167040000.0-182350000.0-167950000.0-187440000.0-216590000.0-195180000.0-160640000.0-195720000.0-196610000.0-148650000.0-128410000.0
Percentage of NetCashProvidedByUsedInInvestingActivities81.785.987.281.985.383.677.993.971.577.543.590.683.483.3
Percentage of RegulatedAndUnregulatedOperatingRevenue-17.6-14.0-17.5-21.1-24.1-20.1-22.1-29.9-27.4-19.3-24.9-29.4-22.2-17.0
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation0.00.0-42.7-79.2-69.5-33.4-49.4-103.1-75.4-30.9-52.9-90.4-53.9-26.0

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value77206104-84.314248-59.034139120124303459081-4.795171114
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue9.523.311.4-10.732.8-7.116.516.617.43.743.913.612.1-0.623.219.3

us-gaap:NetCashProvidedByUsedInFinancingActivities dei:LegalEntity

swx:SouthwestGasCorporation


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value66228167-60.962222-75.051172133603314312243-28.655
Percentage of NetCashProvidedByUsedInFinancingActivities84.9110.8161.072.389.3127.1123.7110.649.1108.541.6135.352.9597.6
Percentage of RegulatedAndUnregulatedOperatingRevenue8.025.818.4-7.729.3-9.020.418.48.64.018.318.46.4-3.8
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation0.00.044.8-28.984.6-14.945.563.523.66.438.856.515.6-5.8

Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-44.788.99359-175.6461381121-9.966-58.591111634-30.38521-15.5329
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue-5.51.06.5-22.218.31.42.5-1.4-8.21.42.15.2-4.52.8-2.15.0

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect dei:LegalEntity

swx:SouthwestGasCorporation


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-12.0778.72518-168.551341623-15.632-42.70543-17.10328-24.8897.843-8.52124
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect27.097.031.796.096.9140.3112.4156.972.9369.9-105.681.881.936.554.981.6
Percentage of RegulatedAndUnregulatedOperatingRevenue-1.51.02.1-21.317.71.92.8-2.2-6.05.2-2.24.2-3.71.0-1.24.1
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation0.00.05.0-79.951.23.26.2-7.4-16.58.3-4.612.9-9.01.6-2.311.3

Increase Decrease In Accounts Payable

us-gaap:IncreaseDecreaseInAccountsPayable

us-gaap:IncreaseDecreaseInAccountsPayable


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value0.072-41.14751-11.83313-60.723442.076-35.512-12.64360-4.1534.032-48.49746234.851-55.298468.4161.768-35.126
Percentage of IncreaseDecreaseInAccountsPayable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInAccountsPayable dei:LegalEntity

swx:SouthwestGasCorporation


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-23.442-33.076593.398-11.813-41.89949-2.524-35.213-39.57476-1.122-17.531-34.564509.735-10.971-44.73663-4.379-10.357-32.324
Percentage of IncreaseDecreaseInAccountsPayable-32558.380.4116.7-28.7-87.369.0112.7-121.699.2313.0126.927.0-434.871.3108.141.1-226.280.9135.6-52.0-585.892.0

Increase Decrease In Accounts Receivable

us-gaap:IncreaseDecreaseInAccountsReceivable

us-gaap:IncreaseDecreaseInAccountsReceivable


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value32-42.8926.6333255-45.8373417-12.951514-11.04521-8.858251833-36.889-1.56524-7.382-45.525
Percentage of IncreaseDecreaseInAccountsReceivable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInAccountsReceivable dei:LegalEntity

swx:SouthwestGasCorporation


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-55.6492766-13.082-55.072-1.97577-19.901-77.043069-13.55-64.3052851-6.334-44.5567.07250-12.492-51.279-27.909
Percentage of IncreaseDecreaseInAccountsReceivable-169.2-64.4998.0-40.4-99.14.3223.1-117.0594.9195.4492.6122.7-298.2-318.4201.9-33.6-133.6-19.2-3255.5-51.2694.661.3

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInOperatingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value53-52.457138112103271121100901881211606618070101
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue6.6-5.915.114.213.732.514.413.812.722.615.424.09.923.99.517.0

us-gaap:NetCashProvidedByUsedInOperatingActivities dei:LegalEntity

swx:SouthwestGasCorporation


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value66-95.4321159942593867911703510180164
Percentage of NetCashProvidedByUsedInOperatingActivities122.7181.98.052.891.395.431.467.6101.390.628.863.5121.491.3
Percentage of RegulatedAndUnregulatedOperatingRevenue8.0-10.81.27.512.531.04.59.312.820.44.515.312.021.9
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation0.00.02.928.236.051.510.132.235.432.79.546.829.333.4

Net Income Loss

us-gaap:NetIncomeLoss

us-gaap:NetIncomeLoss


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value25117103183772915.35322946912217996101769652.4728.9437566-4.7344.94971581.979.62770
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue3.113.211.32.35.08.710.80.73.111.48.81.83.210.513.01.73.210.610.20.51.610.39.6-0.90.99.89.40.52.111.6

us-gaap:NetIncomeLoss dei:LegalEntity

swx:SouthwestGasCorporation


Net
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value11118-15.9731183-20.0123.36910359-13.672.6229074-4.0249.52276652.4728.9437566-4.7344.94971
Percentage of NetIncomeLoss45.4101.2-87.431.5115.2-373.815.3109.085.9-110.912.2114.277.1-39.453.3111.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue1.413.4-2.01.610.0-2.80.512.47.6-2.00.412.010.0-0.71.711.810.20.51.610.39.6-0.90.99.8
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation0.00.0-7.64.616.6-9.51.319.916.1-6.31.018.320.3-1.93.716.610.20.51.610.39.6-0.90.99.8

us-gaap:NetIncomeLoss us-gaap:ConsolidationItems

us-gaap:MaterialReconcilingItems


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-1.41-0.5630.068-0.627-0.244-0.853-0.386-0.473-0.231-0.549-0.18-0.797-0.307-0.257-0.56-0.107
Percentage of NetIncomeLoss-5.6-0.50.1-3.4-0.6-1.2-0.4-8.8-1.0-0.6-0.3-6.5-1.4-0.3-0.6-1.0
Percentage of RegulatedAndUnregulatedOperatingRevenue-0.2-0.10.0-0.1-0.0-0.1-0.0-0.1-0.0-0.1-0.0-0.1-0.0-0.0-0.1-0.0
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:MaterialReconcilingItems0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:NetIncomeLoss us-gaap:StatementBusinessSegments

swx:NaturalGasOperations


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value1111879-15.973118376-20.0123.36910359-13.672.6229074-4.0249.5227651-12.4052.35877
Percentage of NetIncomeLoss45.4101.276.8-87.431.5115.283.3-373.815.3109.085.9-110.912.2114.277.1-39.453.3111.079.6-501.826.4102.8
Percentage of RegulatedAndUnregulatedOperatingRevenue1.413.48.7-2.01.610.09.0-2.80.512.47.6-2.00.412.010.0-0.71.711.88.1-2.30.410.6
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:NaturalGasOperations0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

swx:UtilityInfrastructureServicesSegment


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value15-0.859233426-10.204152518-8.0319.9432619-11.001
Percentage of NetIncomeLoss60.2-0.723.1190.869.2-14.117.1482.785.8-8.514.3217.389.3-13.9
Percentage of RegulatedAndUnregulatedOperatingRevenue1.8-0.12.64.43.5-1.21.83.62.7-1.01.34.02.9-1.5
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:UtilityInfrastructureServicesSegment0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Profit Loss

us-gaap:ProfitLoss

us-gaap:ProfitLoss


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value26118105213973916.525229513112217896101869652.9079.0997566-4.215.06371581.9279.62770
Percentage of ProfitLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue3.213.411.52.75.38.710.80.93.211.416.71.83.210.413.01.83.210.510.20.51.710.39.7-0.80.99.89.40.42.111.6

us-gaap:ProfitLoss dei:LegalEntity

swx:SouthwestGasCorporation


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value1111879-15.973118376-20.0123.36910359-13.672.6229074-4.0249.52276657.422.35877
Percentage of ProfitLoss43.199.975.7-75.829.9114.583.2-306.714.8108.445.4-110.912.2115.477.2-38.652.5111.5100.0255.225.9103.0
Percentage of RegulatedAndUnregulatedOperatingRevenue1.413.48.7-2.01.610.09.0-2.80.512.47.6-2.00.412.010.0-0.71.711.810.21.40.410.6
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation0.00.021.2-7.64.616.620.1-9.51.319.916.1-6.31.018.320.3-1.93.716.610.21.40.410.6

Share Based Compensation

us-gaap:ShareBasedCompensation

us-gaap:ShareBasedCompensation


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value2.0783.6581.3251.4571.5162.8160.8291.3651.5143.1881.4251.3861.4391.8611.6891.4681.626.1111.1090.8332.121.394
Percentage of ShareBasedCompensation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ShareBasedCompensation dei:LegalEntity

swx:SouthwestGasCorporation


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value1.2512.9080.8020.9980.9982.4960.4360.951.1632.5971.0861.0491.1022.1181.2891.0681.225.7111.1090.8332.121.394
Percentage of ShareBasedCompensation60.279.560.568.565.888.652.669.676.881.576.275.776.6113.876.372.875.393.5100.0100.0100.0100.0

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-176520000.0-144860000.0-183560000.0-203970000.0-213750000.0-200790000.0-240620000.0-230540000.0-273150000.0-207320000.0-449990000.0-217000000.0-178290000.0-154210000.0-258100000.0-186030000.0
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue-21.5-16.4-20.1-25.8-28.2-24.0-28.4-31.8-38.3-24.9-57.2-32.5-26.6-20.4-34.9-31.4

us-gaap:NetCashProvidedByUsedInInvestingActivities dei:LegalEntity

swx:SouthwestGasCorporation


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-144220000.0-124380000.0-160060000.0-167040000.0-182350000.0-167950000.0-187440000.0-216590000.0-195180000.0-160640000.0-195720000.0-196610000.0-148650000.0-128410000.0
Percentage of NetCashProvidedByUsedInInvestingActivities81.785.987.281.985.383.677.993.971.577.543.590.683.483.3
Percentage of RegulatedAndUnregulatedOperatingRevenue-17.6-14.0-17.5-21.1-24.1-20.1-22.1-29.9-27.4-19.3-24.9-29.4-22.2-17.0
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation0.00.0-42.7-79.2-69.5-33.4-49.4-103.1-75.4-30.9-52.9-90.4-53.9-26.0

Payments To Acquire Property Plant And Equipment

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value185152192209212210218247260210205221184154173187146115125139152112
Percentage of PaymentsToAcquirePropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment dei:LegalEntity

swx:SouthwestGasCorporation


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value14712816617018117319122220116319620015413116417112310111912312489
Percentage of PaymentsToAcquirePropertyPlantAndEquipment79.684.286.781.785.182.387.589.677.377.795.790.583.685.295.091.384.087.295.288.581.979.7

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value77206104-84.314248-59.034139120124303459081-4.795171114
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue9.523.311.4-10.732.8-7.116.516.617.43.743.913.612.1-0.623.219.3

us-gaap:NetCashProvidedByUsedInFinancingActivities dei:LegalEntity

swx:SouthwestGasCorporation


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value66228167-60.962222-75.051172133603314312243-28.655
Percentage of NetCashProvidedByUsedInFinancingActivities84.9110.8161.072.389.3127.1123.7110.649.1108.541.6135.352.9597.6
Percentage of RegulatedAndUnregulatedOperatingRevenue8.025.818.4-7.729.3-9.020.418.48.64.018.318.46.4-3.8
Percentage of RegulatedAndUnregulatedOperatingRevenue swx:SouthwestGasCorporation0.00.044.8-28.984.6-14.945.563.523.66.438.856.515.6-5.8

Proceeds From Issuance Of Long Term Debt

us-gaap:ProceedsFromIssuanceOfLongTermDebt

us-gaap:ProceedsFromIssuanceOfLongTermDebt


Proceeds
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value71101130520994861391298425120335302235426153124649
Percentage of ProceedsFromIssuanceOfLongTermDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromIssuanceOfLongTermDebt dei:LegalEntity

swx:SouthwestGasCorporation


Proceeds
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-31
Value0.00.04460.00.00.02970.00.00.00.02970.00.0
Percentage of ProceedsFromIssuanceOfLongTermDebt0.00.085.80.00.00.075.80.00.00.00.088.70.00.0

Repayments Of Long Term Debt

us-gaap:RepaymentsOfLongTermDebt

us-gaap:RepaymentsOfLongTermDebt


Repayments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value39216717142758673223194427921238401247581431042
Percentage of RepaymentsOfLongTermDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RepaymentsOfLongTermDebt dei:LegalEntity

swx:SouthwestGasCorporation


Repayments
Period End2020-12-312018-12-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value0.00.00.00.00.0250.0
Percentage of RepaymentsOfLongTermDebt0.00.00.00.00.052.30.0

Payments Of Dividends Common Stock

us-gaap:PaymentsOfDividendsCommonStock

us-gaap:PaymentsOfDividendsCommonStock


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value34323231313029292927252525232323232121212119
Percentage of PaymentsOfDividendsCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsOfDividendsCommonStock dei:LegalEntity

swx:SouthwestGasCorporation


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value27262726252524242223222222212120211821212119
Percentage of PaymentsOfDividendsCommonStock79.779.783.982.882.484.083.683.478.385.185.686.187.588.188.987.590.886.5100.0100.0100.0100.0

Effective Income Tax Rate Continuing Operations

us-gaap:EffectiveIncomeTaxRateContinuingOperations

us-gaap:EffectiveIncomeTaxRateContinuingOperations


Effective
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value024.0-2.423.7600.24-0.035000.240.013
Percentage of EffectiveIncomeTaxRateContinuingOperations0.0100.0100.0100.00.0100.0100.00.00.0100.0100.0

Deferred Tax Liabilities

us-gaap:DeferredTaxLiabilities

us-gaap:DeferredTaxLiabilities


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value646796725637908844
Percentage of DeferredTaxLiabilities100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilities dei:LegalEntity

swx:SouthwestGasCorporation


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value581674651589855
Percentage of DeferredTaxLiabilities89.884.789.792.494.1

Deferred Tax Assets Net

us-gaap:DeferredTaxAssetsNet

us-gaap:DeferredTaxAssetsNet


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value1921971981626975
Percentage of DeferredTaxAssetsNet100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsNet dei:LegalEntity

swx:SouthwestGasCorporation


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value11813516014349
Percentage of DeferredTaxAssetsNet61.668.681.288.771.2

Unrecognized Tax Benefits

us-gaap:UnrecognizedTaxBenefits

us-gaap:UnrecognizedTaxBenefits


Unrecognized
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-31
Value1928000.01056000.0971000.01430000.01231000.0296000.0305000.0
Percentage of UnrecognizedTaxBenefits100.0100.0100.0100.0100.0100.0100.0

us-gaap:UnrecognizedTaxBenefits dei:LegalEntity

swx:SouthwestGasCorporation


Unrecognized
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value1793000.01056000.0971000.01069000.0903000.0
Percentage of UnrecognizedTaxBenefits93.0100.0100.074.873.4

Deferred Tax Assets Valuation Allowance

us-gaap:DeferredTaxAssetsValuationAllowance

us-gaap:DeferredTaxAssetsValuationAllowance


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value22000.025000.01132000.0728000.0495000.0499000.0
Percentage of DeferredTaxAssetsValuationAllowance100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsValuationAllowance dei:LegalEntity

swx:SouthwestGasCorporation


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value22000.025000.037000.058000.0223000.0
Percentage of DeferredTaxAssetsValuationAllowance100.0100.03.38.045.1

Proceeds From Repayments Of Short Term Debt

us-gaap:ProceedsFromRepaymentsOfShortTermDebt

us-gaap:ProceedsFromRepaymentsOfShortTermDebt


Proceeds
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302016-12-312016-09-302016-06-302016-03-31
Value8.020353-4.0-99.0-54.018130-188.0361209.00.0-192.01041080.00.00.0-18.0
Percentage of ProceedsFromRepaymentsOfShortTermDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.00.00.00.0100.0

us-gaap:ProceedsFromRepaymentsOfShortTermDebt dei:LegalEntity

swx:SouthwestGasCorporation


Proceeds
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312016-09-302016-06-302016-03-31
Value24210570.0-97.0-97.016430-188.0361439.00.0-191.01080.00.00.0-18.0
Percentage of ProceedsFromRepaymentsOfShortTermDebt300.0103.4107.5-0.098.0179.690.6100.0100.0100.0118.7100.00.099.5103.80.00.00.0100.0

swx:AdjustmentsToAdditionalPaidInCapitalContributionsFromParent dei:LegalEntity, us-gaap:StatementEquityComponents

swx:AdjustmentsToAdditionalPaidInCapitalContributionsFromParent

swx:SouthwestGasCorporation, us-gaap:AdditionalPaidInCapital


Adjustments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value6945453249503324792222345629
Percentage of AdjustmentsToAdditionalPaidInCapitalContributionsFromParent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

swx:AlternativeRevenueProgramRevenuesDeferrals

swx:AlternativeRevenueProgramRevenuesDeferrals


Alternative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-1.531-16.3732.5959.1994.111-3.765-1.9167.9573.392-34.545-0.7179.0941027209.12310-4.232
Percentage of AlternativeRevenueProgramRevenuesDeferrals100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

swx:AmountsBilledInExcessOfRevenueEarnedOnContracts

swx:AmountsBilledInExcessOfRevenueEarnedOnContracts


Amounts
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value-1111000.01917000.04716000.0-1611000.0-650000.02198000.04588000.0-2981000.0
Percentage of AmountsBilledInExcessOfRevenueEarnedOnContracts100.0100.0100.0100.0100.0100.0100.0100.0

swx:ChangesInCustomerAdvancesInvestingActivities

swx:ChangesInCustomerAdvancesInvestingActivities


Changes
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value3.2214.2866.3423.593-1.3365.4343.9525.5666.4053.078
Percentage of ChangesInCustomerAdvancesInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

swx:ChangesInCustomerAdvancesInvestingActivities dei:LegalEntity

swx:SouthwestGasCorporation


Changes
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value3.2224.2856.3423.593-1.3355.4333.9525.5666.4053.078
Percentage of ChangesInCustomerAdvancesInvestingActivities100.0100.0100.0100.099.9100.0100.0100.0100.0100.0

swx:CommonStockWeightedAverageIssuePricePerShare us-gaap:SubsidiarySaleOfStock

swx:CommonStockWeightedAverageIssuePricePerShare

swx:EquityShelfProgram


Common
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-03-312018-12-312018-03-312017-12-31
Value66.9765.867.1864.7769.42-2.5488.9683.05067.083.65
Percentage of CommonStockWeightedAverageIssuePricePerShare100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0

swx:DeferredPurchasedGasCostsEstimatedIncrementalCosts

swx:DeferredPurchasedGasCostsEstimatedIncrementalCosts


Deferred
Period End2021-03-31
Value250
Percentage of DeferredPurchasedGasCostsEstimatedIncrementalCosts100.0

swx:DeferredPurchasedGasCostsEstimatedIncrementalCosts us-gaap:Range, us-gaap:SubsequentEventType

srt:Maximum, us-gaap:SubsequentEvent


Deferred
Period End2021-02-25
Value300
Percentage of DeferredPurchasedGasCostsEstimatedIncrementalCosts0.0

srt:Minimum, us-gaap:SubsequentEvent


Deferred
Period End2021-02-25
Value200
Percentage of DeferredPurchasedGasCostsEstimatedIncrementalCosts0.0

swx:DeferredPurchasedGasCostsPipelineImbalanceCharges

swx:DeferredPurchasedGasCostsPipelineImbalanceCharges


Deferred
Period End2021-05-312021-02-28
Value5565
Percentage of DeferredPurchasedGasCostsPipelineImbalanceCharges100.0100.0

swx:IncreaseDecreaseInAccruedTaxes

swx:IncreaseDecreaseInAccruedTaxes


Increase
Period End2020-09-302020-06-302020-03-312019-09-302019-06-302019-03-31
Value8.972-21.35830-0.569-27.67225
Percentage of IncreaseDecreaseInAccruedTaxes100.0100.0100.0100.0100.0100.0

swx:IncreaseDecreaseInAccruedTaxes dei:LegalEntity

swx:SouthwestGasCorporation


Increase
Period End2020-09-302020-06-302020-03-312019-09-302019-06-302019-03-31
Value-1.832-35.58953-4.367-28.75628
Percentage of IncreaseDecreaseInAccruedTaxes-20.4166.6175.6767.5103.9113.0

swx:LineOfCreditFacilityMinimumAmountOutstandingDuringPeriod dei:LegalEntity, us-gaap:LongtermDebtType

swx:LineOfCreditFacilityMinimumAmountOutstandingDuringPeriod

swx:CenturiGroupInc., swx:SecuredRevolvingCreditFacilityTermLoan


Line
Period End2020-12-312019-03-31
Value276.0
Percentage of LineOfCreditFacilityMinimumAmountOutstandingDuringPeriod100.0100.0

swx:MiscellaneousIncomeExpense dei:LegalEntity, us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

swx:MiscellaneousIncomeExpense

swx:CenturiGroupInc., us-gaap:OperatingSegments, swx:UtilityInfrastructureServicesSegment


Miscellaneous
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-137000.0-99000.0-180000.048000.093000.0-232000.0-542000.0177000.0-498000.0344000.0-40000.0125000.0-835000.0115000.0
Percentage of MiscellaneousIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

swx:SouthwestGasCorporation, us-gaap:OperatingSegments, swx:NaturalGasOperations


Miscellaneous
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-1010000.0-342000.0-949000.0-388000.0-690000.0-2480000.0-1502000.0-521000.0-872000.0-446000.0-1226000.0-553000.0-564000.0-285000.0-363000.0-657000.0
Percentage of MiscellaneousIncomeExpense737.2345.5527.2-808.3-741.91069.0277.1-294.4175.1-129.73065.0-442.467.5-247.80.00.0

swx:NumberOfPerformanceShareUnitsGranted

swx:NumberOfPerformanceShareUnitsGranted


Number
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value95000.075000.076000.063000.050000.0-2000.055000.049000.040000.0
Percentage of NumberOfPerformanceShareUnitsGranted100.0100.0100.0100.0100.0100.0100.0100.0100.0

swx:OtherComprehensiveIncomeDefinedBenefitPlansRegulatoryAdjustmentNetOfTax

swx:OtherComprehensiveIncomeDefinedBenefitPlansRegulatoryAdjustmentNetOfTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value7.2777.277-24.796.386.386.38-40.274.0654.0644.063-10.9795.7465.7445.746-23.2573.5553.5563.556-7.9263.7963.7963.796
Percentage of OtherComprehensiveIncomeDefinedBenefitPlansRegulatoryAdjustmentNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

swx:OtherComprehensiveIncomeDefinedBenefitPlansRegulatoryAdjustmentNetOfTax dei:LegalEntity

swx:SouthwestGasCorporation


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value7.2777.277-24.796.386.386.38-40.274.0654.0644.063-10.9795.7465.7445.746-23.2573.5553.5563.556-7.9263.7963.7963.796
Percentage of OtherComprehensiveIncomeDefinedBenefitPlansRegulatoryAdjustmentNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

swx:OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTaxOther dei:LegalEntity, us-gaap:StatementEquityComponents

swx:OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTaxOther

swx:SouthwestGasCorporation, us-gaap:AccumulatedOtherComprehensiveIncome


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-1377000.0-1379000.011533000.0-1027000.0-1027000.0-1028000.010499000.0-618000.0-619000.0-619000.0-2096000.0-895000.0-897000.0-895000.0
Percentage of OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTaxOther100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

swx:OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTaxOther us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-1377000.0-1379000.011533000.0-1027000.0-1027000.0-1028000.010499000.0-618000.0-619000.0-619000.0-2096000.0-895000.0-897000.0-895000.0
Percentage of OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTaxOther100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

swx:OtherRevenue

swx:OtherRevenue


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value2.9832.785-0.315-1.447-0.7431.7992.0371.7671.9113.0422.05113.587-11.454-0.6761.7771.7851.194
Percentage of OtherRevenue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

swx:ProceedsFromIssuanceOfCommonStockGross us-gaap:SubsidiarySaleOfStock

swx:ProceedsFromIssuanceOfCommonStockGross

swx:EquityShelfProgram


Proceeds
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-03-312018-12-312018-03-312017-12-31
Value70464632492424230.09.19966129
Percentage of ProceedsFromIssuanceOfCommonStockGross100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0

swx:ProceedsFromRepaymentsOfLinesOfCreditAndCommercialPaper

swx:ProceedsFromRepaymentsOfLinesOfCreditAndCommercialPaper


Proceeds
Period End2020-09-302020-06-302020-03-312019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value58-150.00.0-104.00.00.01029.0-111.00.0587710.05.0-2.52.5-150.0
Percentage of ProceedsFromRepaymentsOfLinesOfCreditAndCommercialPaper100.0100.00.0100.00.00.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0

swx:ProceedsFromRepaymentsOfLinesOfCreditAndCommercialPaper dei:LegalEntity

swx:SouthwestGasCorporation


Proceeds
Period End2020-09-302020-06-302020-03-312019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value58-150.00.0-104.00.00.01029.0-111.00.0587710.05.0-2.52.5-150.0
Percentage of ProceedsFromRepaymentsOfLinesOfCreditAndCommercialPaper100.0100.00.0100.00.00.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0

swx:RevenueEarnedOnContractsInProgressInExcessOfBillings

swx:RevenueEarnedOnContractsInProgressInExcessOfBillings


Revenue
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value114599-22.4553.32520971.966
Percentage of RevenueEarnedOnContractsInProgressInExcessOfBillings100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:BusinessCombinationConsiderationTransferred1 us-gaap:BusinessAcquisition

us-gaap:BusinessCombinationConsiderationTransferred1

swx:DrumParentInc


Business
Period End2021-06-30
Value855
Percentage of BusinessCombinationConsiderationTransferred1100.0

us-gaap:ContractWithCustomerAssetReclassifiedToReceivable

us-gaap:ContractWithCustomerAssetReclassifiedToReceivable


Contract
Period End2021-06-302021-03-31
Value22107
Percentage of ContractWithCustomerAssetReclassifiedToReceivable100.0100.0

us-gaap:ContractWithCustomerLiabilityRevenueRecognized

us-gaap:ContractWithCustomerLiabilityRevenueRecognized


Contract
Period End2021-06-302021-03-312020-12-31
Value04500000.00
Percentage of ContractWithCustomerLiabilityRevenueRecognized0.0100.00.0

us-gaap:DefinedBenefitPlanActuarialGainLossImmediateRecognitionAsComponentInNetPeriodicBenefitCostCredit dei:LegalEntity, us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:DefinedBenefitPlanActuarialGainLossImmediateRecognitionAsComponentInNetPeriodicBenefitCostCredit

swx:SouthwestGasCorporation, us-gaap:OperatingSegments, swx:NaturalGasOperations


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-3505000.0-3505000.0-5006000.0-5005000.0-5006000.0-5005000.0-3764000.0-3765000.0-3765000.0-3765000.0-5265000.0-5265000.0-5264000.0-5265000.0-4856000.0-4856000.0
Percentage of DefinedBenefitPlanActuarialGainLossImmediateRecognitionAsComponentInNetPeriodicBenefitCostCredit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DefinedBenefitPlanAmortizationOfGainsLosses us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanAmortizationOfGainsLosses

us-gaap:OtherPensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value-10489000.0-10489000.0-9006000.0-9006000.0-9006000.0-9007000.0-5589000.0-5589000.0-5589000.0-5589000.0-8029000.0-8029000.0-8028000.0-8029000.0-6001000.0-6001000.0-6001000.0-6001000.0-6316000.0-6317000.0-6316000.0
Percentage of DefinedBenefitPlanAmortizationOfGainsLosses100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:SupplementalEmployeeRetirementPlanDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value-660000.0-660000.0-452000.0-451000.0-451000.0-451000.0-255000.0-255000.0-255000.0-255000.0-376000.0-375000.0-376000.0-375000.0-360000.0-361000.0-360000.0-360000.0-345000.0-346000.0-346000.0
Percentage of DefinedBenefitPlanAmortizationOfGainsLosses6.36.35.05.05.05.04.64.64.64.64.74.74.74.76.06.06.06.05.55.55.5

us-gaap:DefinedBenefitPlanAmortizationOfPriorServiceCostCredit us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanAmortizationOfPriorServiceCostCredit

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value240000.0240000.0288000.0289000.0289000.0289000.0318000.0318000.0318000.0317000.0333000.0334000.0334000.0334000.0334000.0333000.0334000.0334000.0334000.0333000.0334000.0
Percentage of DefinedBenefitPlanAmortizationOfPriorServiceCostCredit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DefinedBenefitPlanExpectedReturnOnPlanAssets us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanExpectedReturnOnPlanAssets

us-gaap:OtherPensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value181816161616151515151414141413131313141414
Percentage of DefinedBenefitPlanExpectedReturnOnPlanAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value0.810.810.8520.8520.8520.8520.7890.7890.7890.7890.9290.9290.930.930.840.8390.8390.840.7870.7870.787
Percentage of DefinedBenefitPlanExpectedReturnOnPlanAssets4.54.55.25.25.25.25.25.25.25.26.36.36.36.36.16.16.16.15.65.65.6

us-gaap:DefinedBenefitPlanInterestCost us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanInterestCost

us-gaap:OtherPensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value101011111111121212121111111111111111111111
Percentage of DefinedBenefitPlanInterestCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value0.5480.5480.6460.6460.6450.6450.7610.7610.7620.7620.6870.6870.6870.6870.8080.8080.8080.8080.7940.7950.795
Percentage of DefinedBenefitPlanInterestCost5.45.45.75.75.75.76.26.26.26.26.26.26.26.27.07.07.07.06.96.96.9

us-gaap:SupplementalEmployeeRetirementPlanDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value0.3580.3580.40.4010.4020.4010.440.440.440.440.4140.4150.4140.4150.470.4710.4710.4710.4650.4640.465
Percentage of DefinedBenefitPlanInterestCost3.53.53.53.53.53.53.63.63.63.63.73.83.73.84.14.14.14.14.04.04.0

us-gaap:DefinedBenefitPlanNetPeriodicBenefitCost us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanNetPeriodicBenefitCost

us-gaap:OtherPensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value1212121212129.2459.2469.2459.246111111119.5729.579.5719.579.3929.3929.392
Percentage of DefinedBenefitPlanNetPeriodicBenefitCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value0.4010.4010.4770.4780.4770.4780.6090.6090.610.6090.4590.460.460.4590.6690.6690.670.6690.8210.820.821
Percentage of DefinedBenefitPlanNetPeriodicBenefitCost3.13.13.83.83.83.86.66.66.66.64.04.04.04.07.07.07.07.08.78.78.7

us-gaap:SupplementalEmployeeRetirementPlanDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value1.151.1490.9490.9490.950.950.7620.7610.7620.7610.8520.8510.8510.8510.9070.9090.9080.9090.8930.8930.894
Percentage of DefinedBenefitPlanNetPeriodicBenefitCost9.09.07.57.57.57.58.28.28.28.27.47.47.47.49.59.59.59.59.59.59.5

us-gaap:DefinedBenefitPlanServiceCost us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanServiceCost

us-gaap:OtherPensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value10108.5748.5768.5758.5746.4666.4666.4666.4667.1387.1397.1397.1395.8485.8485.8485.8485.7085.7085.708
Percentage of DefinedBenefitPlanServiceCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value0.4230.4230.3950.3950.3950.3960.3190.3190.3190.3190.3680.3680.3690.3680.3670.3670.3670.3670.3750.3750.375
Percentage of DefinedBenefitPlanServiceCost4.14.14.64.64.64.64.94.94.94.95.25.25.25.26.36.36.36.36.66.66.6

us-gaap:SupplementalEmployeeRetirementPlanDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value0.1320.1310.0970.0970.0970.0980.0670.0660.0670.0660.0620.0610.0610.0610.0770.0770.0770.0780.0830.0830.083
Percentage of DefinedBenefitPlanServiceCost1.31.31.11.11.11.11.01.01.01.00.90.90.90.91.31.31.31.31.51.51.5

us-gaap:DepreciationAndAmortization

us-gaap:DepreciationAndAmortization


Depreciation
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value82938780778779757077636261626158587271697275
Percentage of DepreciationAndAmortization100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DepreciationAndAmortization dei:LegalEntity

swx:SouthwestGasCorporation


Depreciation
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value57686155536456524957464747494846466159565760
Percentage of DepreciationAndAmortization69.673.570.669.868.973.870.469.570.174.373.177.177.780.078.078.979.684.482.780.878.980.6

us-gaap:DividendsCommonStock dei:LegalEntity, us-gaap:StatementEquityComponents

us-gaap:DividendsCommonStock

swx:SouthwestGasCorporation, us-gaap:RetainedEarnings


Dividends
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value282726272625252424222322222220212018
Percentage of DividendsCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DividendsCommonStock us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings


Dividends
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value353432323231302929292725252524232323
Percentage of DividendsCommonStock124.0126.8125.9119.7121.3122.8119.6120.2120.6128.4118.1117.6117.0115.2114.3113.4115.4128.2

us-gaap:EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

us-gaap:EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents


Effect
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value85000.0103000.0437000.0-39000.0145000.0-315000.0100000.0-14000.07000.065000.0-347000.0263000.0-53000.0-71000.018000.0140000.0
Percentage of EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FinanceLeasePrincipalPayments

us-gaap:FinanceLeasePrincipalPayments


Finance
Period End2020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value49000.051000.051000.054000.037000.070000.0106000.0151000.0165000.0
Percentage of FinanceLeasePrincipalPayments100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ForeignCurrencyTransactionGainLossRealized dei:LegalEntity, us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:ForeignCurrencyTransactionGainLossRealized

swx:CenturiGroupInc., us-gaap:OperatingSegments, swx:UtilityInfrastructureServicesSegment


Foreign
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-9000.0-3000.000-6000.0-10000.00-6000.021000.0531000.0-480000.0-91000.0202000.0147000.0
Percentage of ForeignCurrencyTransactionGainLossRealized100.0100.00.00.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:GainLossOnSaleOfPropertyPlantEquipment

us-gaap:GainLossOnSaleOfPropertyPlantEquipment


Gain
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value2524000.01509000.01267000.0272000.0281000.028000.02316000.02326000.0598000.0233000.0706000.0747000.020000.0230000.02744000.025000.01088000.0339000.03031000.01375000.01409000.01333000.0
Percentage of GainLossOnSaleOfPropertyPlantEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:GoodwillForeignCurrencyTranslationGainLoss

us-gaap:GoodwillForeignCurrencyTranslationGainLoss


Goodwill
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value1620000.01369000.04987000.02219000.04035000.0-9080000.02068000.0-1256000.02204000.02134000.0-5508000.01826000.0-2252000.0-3011000.0-579000.04282000.02609000.0991000.0
Percentage of GoodwillForeignCurrencyTranslationGainLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:GoodwillForeignCurrencyTranslationGainLoss us-gaap:StatementBusinessSegments

swx:UtilityInfrastructureServicesSegment


Goodwill
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value1620000.01369000.04987000.02219000.04035000.0-9080000.02068000.0-1256000.02204000.02134000.0
Percentage of GoodwillForeignCurrencyTranslationGainLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInAccruedTaxesPayable

us-gaap:IncreaseDecreaseInAccruedTaxesPayable


Increase
Period End2021-06-302021-03-312020-06-302020-03-312019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-37.834-21.35830-27.67225-2.1157.51-36.12618-2.57710-26.49720335.066-50.31738
Percentage of IncreaseDecreaseInAccruedTaxesPayable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInAccruedTaxesPayable dei:LegalEntity

swx:SouthwestGasCorporation


Increase
Period End2021-06-302021-03-312020-06-302020-03-312019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-39.4541-35.58953-28.75628-2.706-3.25-40.252276.2916.915-27.99925250.796-42.50536
Percentage of IncreaseDecreaseInAccruedTaxesPayable104.4120.8166.6175.6103.9113.0127.9-43.3111.4146.3-244.164.1105.7123.475.015.784.594.4

us-gaap:IncreaseDecreaseInAllowanceForEquityFundsUsedDuringConstruction

us-gaap:IncreaseDecreaseInAllowanceForEquityFundsUsedDuringConstruction


Increase
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value981000.01311000.01232000.01120000.01061000.0982000.01212000.01007000.0960000.02593000.0448000.0357000.0229000.0219000.0968000.0634000.0475000.0396000.0611000.0750000.0532000.0
Percentage of IncreaseDecreaseInAllowanceForEquityFundsUsedDuringConstruction100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInAllowanceForEquityFundsUsedDuringConstruction dei:LegalEntity

swx:SouthwestGasCorporation


Increase
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value981000.01311000.01232000.01120000.01061000.0982000.01212000.01007000.0960000.02593000.0448000.0357000.0229000.0219000.0968000.0634000.0475000.0396000.0611000.0750000.0532000.0
Percentage of IncreaseDecreaseInAllowanceForEquityFundsUsedDuringConstruction100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInContractWithCustomerAsset

us-gaap:IncreaseDecreaseInContractWithCustomerAsset


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value-12000000.0-31900000.045900000.0700000.0-12300000.0-31000000.043300000.0900000.0-12100000.0-30200000.0
Percentage of IncreaseDecreaseInContractWithCustomerAsset100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInContractWithCustomerAsset dei:LegalEntity

swx:SouthwestGasCorporation


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value-12000000.0-31900000.045900000.0700000.0-12300000.0-31000000.043300000.0900000.0-12100000.0-30200000.0
Percentage of IncreaseDecreaseInContractWithCustomerAsset100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInDeferredGasCost

us-gaap:IncreaseDecreaseInDeferredGasCost


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-3.78229123-6.304-43.44-10.15521-6.733-24.5226718-66.658-44.73310165.9313.2969352.9-25.312-58.977
Percentage of IncreaseDecreaseInDeferredGasCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInDeferredGasCost dei:LegalEntity

swx:SouthwestGasCorporation


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-3.78229123-6.304-43.44-10.15521-6.733-24.5226718-66.658-44.73310165.9313.2969352.9-25.312-58.977
Percentage of IncreaseDecreaseInDeferredGasCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInDeferredIncomeTaxes

us-gaap:IncreaseDecreaseInDeferredIncomeTaxes


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-20852000.0-23326000.0-12965000.0-6631000.0-5812000.0-25309000.0-8063000.0-14268000.0-6908000.0-24923000.0-14831000.0-2892000.0-10090000.0-23228000.0-13980000.0-1573000.0-10591000.0-37245000.0-25030000.02214000.0-26985000.0-18931000.0
Percentage of IncreaseDecreaseInDeferredIncomeTaxes100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInDeferredIncomeTaxes dei:LegalEntity

swx:SouthwestGasCorporation


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-23226000.0-14952000.0-19364000.0-7447000.0-10479000.0-7707000.02218000.0-7716000.0-1913000.0-26270000.0-9760000.0-5868000.0-8695000.0-18676000.0-22548000.02253000.0-7651000.0-39223000.0-28006000.0639000.0-21139000.0-19453000.0
Percentage of IncreaseDecreaseInDeferredIncomeTaxes111.464.1149.4112.3180.330.5-27.554.127.7105.465.8202.986.280.4161.3-143.272.2105.3111.928.978.3102.8

us-gaap:IncreaseDecreaseInOtherCurrentAssetsAndLiabilitiesNet

us-gaap:IncreaseDecreaseInOtherCurrentAssetsAndLiabilitiesNet


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value265.25513-42.647-2.085-76.453-0.089-19.06-7.14-47.84855-18.051160.64351-22.6540.709-21.09941-4.261-0.985-6.776
Percentage of IncreaseDecreaseInOtherCurrentAssetsAndLiabilitiesNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInOtherCurrentAssetsAndLiabilitiesNet dei:LegalEntity

swx:SouthwestGasCorporation


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value36-41.01826-3.3827-99.257-1.302-13.287.036-81.625561027-3.16346-8.18813-37.342325.613.613-8.404
Percentage of IncreaseDecreaseInOtherCurrentAssetsAndLiabilitiesNet136.7-780.6191.57.9-1330.7129.81462.969.7-98.5170.6101.8-59.8170.3-491.990.136.11844.4177.078.6-131.7-366.8124.0

us-gaap:IncreaseDecreaseInOtherOperatingAssets

us-gaap:IncreaseDecreaseInOtherOperatingAssets


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value0.79210131014-6.4955.196-0.015-0.45816-4.7595.3753.2771.8457.7992.9494.3487.173-13.034-3.703-0.5140.291
Percentage of IncreaseDecreaseInOtherOperatingAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInOtherOperatingAssets dei:LegalEntity

swx:SouthwestGasCorporation


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value4.00513161317-3.658100.7622.09818-3.9765.5353.4921.9988.0573.064.547.261-12.947-3.615-0.4270.378
Percentage of IncreaseDecreaseInOtherOperatingAssets505.7130.4123.7128.4117.556.3205.3-5080.0-458.1111.783.5103.0106.6108.3103.3103.8104.4101.299.397.683.1129.9

us-gaap:IncreaseDecreaseInOtherOperatingLiabilities

us-gaap:IncreaseDecreaseInOtherOperatingLiabilities


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value5.403-50.416-10.6532.8010.903-55.722-2.978-3.332-3.672-2.78243-10.535-12.292180.8361.1910.6941.51-13.634-2.311-4.2211.719
Percentage of IncreaseDecreaseInOtherOperatingLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInOtherOperatingLiabilities dei:LegalEntity

swx:SouthwestGasCorporation


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value3.473-48.782-12.6042.6410.737-55.91-3.004-3.521-3.859-2.977302.073-12.41170.6581.1880.4971.198-13.634-2.311-4.2211.719
Percentage of IncreaseDecreaseInOtherOperatingLiabilities64.396.8118.394.381.6100.3100.9105.7105.1107.070.0-19.7101.098.078.799.771.679.3100.0100.0100.0100.0

us-gaap:IncrementalCommonSharesAttributableToNonvestedSharesWithForfeitableDividends

us-gaap:IncrementalCommonSharesAttributableToNonvestedSharesWithForfeitableDividends


Incremental
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value103000.079000.08000.086000.070000.053000.0-1000.066000.057000.044000.0
Percentage of IncrementalCommonSharesAttributableToNonvestedSharesWithForfeitableDividends100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InterestIncomeOther dei:LegalEntity, us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:InterestIncomeOther

swx:SouthwestGasCorporation, us-gaap:OperatingSegments, swx:NaturalGasOperations


Interest
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value1231000.0716000.0801000.01412000.0414000.01388000.01416000.01521000.01822000.01597000.01719000.01506000.01377000.01418000.0936000.0670000.0
Percentage of InterestIncomeOther100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LifeInsuranceCorporateOrBankOwnedChangeInValue dei:LegalEntity, us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:LifeInsuranceCorporateOrBankOwnedChangeInValue

swx:SouthwestGasCorporation, us-gaap:OperatingSegments, swx:NaturalGasOperations


Life
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value3.12.78.24.512-15.56.20.23.47.6-9.24.72.0-0.73.52.1
Percentage of LifeInsuranceCorporateOrBankOwnedChangeInValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LineOfCreditFacilityMaximumAmountOutstandingDuringPeriod dei:LegalEntity, us-gaap:LongtermDebtType

us-gaap:LineOfCreditFacilityMaximumAmountOutstandingDuringPeriod

swx:CenturiGroupInc., swx:SecuredRevolvingCreditFacilityTermLoan


Line
Period End2020-09-302019-09-30
Value7799
Percentage of LineOfCreditFacilityMaximumAmountOutstandingDuringPeriod100.0100.0

us-gaap:MinorityInterestChangeInRedemptionValue

us-gaap:MinorityInterestChangeInRedemptionValue


Minority
Period End2021-06-302021-03-312020-12-312020-09-30
Value32385617
Percentage of MinorityInterestChangeInRedemptionValue100.0100.0100.0100.0

us-gaap:MinorityInterestChangeInRedemptionValue us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings


Minority
Period End2021-06-302021-03-312020-12-312020-09-30
Value6.112-38.018-56.94-17.573
Percentage of MinorityInterestChangeInRedemptionValue19.1-100.0-100.0-99.8

us-gaap:NetIncomeLossAttributableToRedeemableNoncontrollingInterest

us-gaap:NetIncomeLossAttributableToRedeemableNoncontrollingInterest


Net
Period End2021-06-302021-03-312020-12-31
Value1355000.01552000.01492000.0
Percentage of NetIncomeLossAttributableToRedeemableNoncontrollingInterest100.0100.0100.0

us-gaap:NetIncomeLossIncludingPortionAttributableToNonredeemableNoncontrollingInterest dei:LegalEntity, us-gaap:StatementEquityComponents

us-gaap:NetIncomeLossIncludingPortionAttributableToNonredeemableNoncontrollingInterest

swx:SouthwestGasCorporation, us-gaap:RetainedEarnings


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1111879-15.973118376-20.0123.36910359-13.672.62290
Percentage of NetIncomeLossIncludingPortionAttributableToNonredeemableNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:NetIncomeLossIncludingPortionAttributableToNonredeemableNoncontrollingInterest us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value25117103183772915.353229469122179
Percentage of NetIncomeLossIncludingPortionAttributableToNonredeemableNoncontrollingInterest220.198.8130.2-114.4317.986.8120.0-26.7654.791.7116.4-90.2821.987.5

us-gaap:OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentBeforeTaxPortionAttributableToParent us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentBeforeTaxPortionAttributableToParent

us-gaap:AccumulatedOtherComprehensiveIncome


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value909000.0823000.02900000.01024000.01794000.0-4005000.0907000.0-447000.0787000.0791000.0-2008000.0599000.0-690000.0-911000.0-90000.01030000.0607000.0213000.0
Percentage of OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentBeforeTaxPortionAttributableToParent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax

us-gaap:OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value182000.0182000.0219000.0220000.0220000.0220000.0242000.0241000.0242000.0241000.0253000.0254000.0254000.0254000.0207000.0207000.0207000.0207000.0207000.0207000.0207000.0207000.0
Percentage of OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax dei:LegalEntity

swx:SouthwestGasCorporation


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value182000.0182000.0219000.0220000.0220000.0220000.0242000.0241000.0242000.0241000.0253000.0254000.0254000.0254000.0207000.0207000.0207000.0207000.0207000.0207000.0207000.0207000.0
Percentage of OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax

us-gaap:AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterest


Other
Period End2021-06-302021-03-31
Value909000.0823000.0
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax100.0100.0

us-gaap:AccumulatedTranslationAdjustment


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value909000.0823000.02900000.01024000.01794000.0-4005000.0907000.0-447000.0787000.0791000.0-2008000.0599000.0-690000.0-911000.0-90000.01012000.0
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax100.0100.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax

us-gaap:OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value909000.0823000.0-40830000.01024000.01794000.0-4005000.0-53119000.0-447000.0787000.0791000.0-17532000.0
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax us-gaap:StatementEquityComponents

us-gaap:AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterest


Other
Period End2021-06-302021-03-31
Value909000.0823000.0
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax100.0100.0

us-gaap:AccumulatedTranslationAdjustment


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value909000.0823000.02900000.01024000.01794000.0-4005000.0907000.0-447000.0787000.0791000.0-2008000.0599000.0-690000.0-911000.0-90000.01012000.0
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax100.0100.0-7.1100.0100.0100.0-1.7100.0100.0100.011.50.00.00.00.00.0

us-gaap:AociIncludingPortionAttributableToNoncontrollingInterest


Other
Period End2021-06-302021-03-31
Value2700000.02615000.0
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax297.0317.7

us-gaap:OtherComprehensiveIncomeLossBeforeTax

us-gaap:OtherComprehensiveIncomeLossBeforeTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value3.2663.181-11.733.4063.981-1.816-12.0731.2032.4372.4411.5862.6131.3251.104-6.0412.8082.4252.016-2.5021.5751.8842.596
Percentage of OtherComprehensiveIncomeLossBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossBeforeTax dei:LegalEntity

swx:SouthwestGasCorporation


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value2.3572.358-14.632.3822.1872.189-12.981.651.651.653.5942.0142.0152.015-5.9511.7961.7961.796-2.0491.8131.8141.814
Percentage of OtherComprehensiveIncomeLossBeforeTax72.274.1124.769.954.9-120.5107.5137.267.767.6226.677.1152.1182.598.564.074.189.181.9115.196.369.9

us-gaap:OtherComprehensiveIncomeLossBeforeTax dei:LegalEntity, us-gaap:StatementEquityComponents

swx:SouthwestGasCorporation, swx:AccumulatedDefinedBenefitPlansAdjustmentRegulartoryAdjustmentAttributabletoParent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value-9.575-9.57532-8.394-8.395-8.39552-5.348-5.348-5.34714
Percentage of OtherComprehensiveIncomeLossBeforeTax-293.2-301.0-278.1-246.4-210.9462.3-438.9-444.6-219.5-219.0910.8

swx:SouthwestGasCorporation, us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value1.8131.814-15.1741.3521.3511.352-13.8160.8140.8140.8142.758
Percentage of OtherComprehensiveIncomeLossBeforeTax55.557.0129.439.733.9-74.4114.467.733.433.3173.9

swx:SouthwestGasCorporation, us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCredit


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value0.240.240.2880.2890.2890.2890.3180.3180.3180.3170.333
Percentage of OtherComprehensiveIncomeLossBeforeTax7.37.5-2.58.57.3-15.9-2.626.413.013.021.0

swx:SouthwestGasCorporation, us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLoss


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value11119.4589.4579.4579.4585.8445.8445.8445.8448.405
Percentage of OtherComprehensiveIncomeLossBeforeTax341.3350.5-80.6277.7237.6-520.8-48.4485.8239.8239.4529.9

swx:SouthwestGasCorporation, us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value0.5440.5440.5441.030.8360.8370.8360.8360.8360.8360.836
Percentage of OtherComprehensiveIncomeLossBeforeTax16.717.1-4.630.221.0-46.1-6.969.534.334.252.7

us-gaap:OtherComprehensiveIncomeLossBeforeTax us-gaap:StatementEquityComponents

swx:AccumulatedDefinedBenefitPlansAdjustmentRegulartoryAdjustmentAttributabletoParent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value-9.575-9.57532-8.394-8.395-8.39552-5.348-5.348-5.34714
Percentage of OtherComprehensiveIncomeLossBeforeTax-293.2-301.0-278.1-246.4-210.9462.3-438.9-444.6-219.5-219.0910.8

us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value1.8131.814-15.1741.3521.3511.352-13.8160.8140.8140.8142.7581.1781.1791.178-6.7880.961
Percentage of OtherComprehensiveIncomeLossBeforeTax55.557.0129.439.733.9-74.4114.467.733.433.3173.945.189.0106.7112.434.2

us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCredit


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value0.240.240.2880.2890.2890.2890.3180.3180.3180.3170.333
Percentage of OtherComprehensiveIncomeLossBeforeTax7.37.5-2.58.57.3-15.9-2.626.413.013.021.0

us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLoss


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value11119.4589.4579.4579.4585.8445.8445.8445.8448.405
Percentage of OtherComprehensiveIncomeLossBeforeTax341.3350.5-80.6277.7237.6-520.8-48.4485.8239.8239.4529.9

us-gaap:AccumulatedTranslationAdjustment


Other
Period End2020-09-302020-06-302020-03-312019-09-302019-06-302019-03-31
Value1.0241.794-4.005-0.4470.7870.791
Percentage of OtherComprehensiveIncomeLossBeforeTax30.145.1220.5-37.232.332.4

us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value0.5440.5440.5441.030.8360.8370.8360.8360.8360.8360.8360.8360.8360.8370.8370.835
Percentage of OtherComprehensiveIncomeLossBeforeTax16.717.1-4.630.221.0-46.1-6.969.534.334.252.732.063.175.8-13.929.7

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value-414000.0-413000.0-413000.0-783000.0-635000.0-636000.0-635000.0-635000.0-636000.0-635000.0
Percentage of OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax dei:LegalEntity

swx:SouthwestGasCorporation


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value-414000.0-413000.0-413000.0-783000.0-635000.0-636000.0-635000.0-635000.0-636000.0-635000.0
Percentage of OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax dei:LegalEntity, us-gaap:StatementEquityComponents

swx:SouthwestGasCorporation, us-gaap:AccumulatedOtherComprehensiveIncome


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value-414000.0-413000.0-413000.0-783000.0-635000.0-636000.0-635000.0-635000.0-636000.0-635000.0
Percentage of OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value-414000.0-413000.0-413000.0-783000.0-635000.0-636000.0-635000.0-635000.0-636000.0-635000.0
Percentage of OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax

us-gaap:OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-1377000.0-1379000.011533000.0-1027000.0-1027000.0-1028000.010499000.0-618000.0-619000.0-619000.0-2096000.0-895000.0-897000.0-895000.05293000.0-596000.0-595000.0-595000.01790000.0-607000.0-605000.0-607000.0
Percentage of OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax dei:LegalEntity

swx:SouthwestGasCorporation


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-1377000.0-1379000.011533000.0-1027000.0-1027000.0-1028000.010499000.0-618000.0-619000.0-619000.0-2096000.0-895000.0-897000.0-895000.05293000.0-596000.0-595000.0-595000.01790000.0-607000.0-605000.0-607000.0
Percentage of OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-8472000.0-8474000.0-7188000.0-7187000.0-7187000.0-7188000.0-4441000.0-4442000.0-4441000.0-4441000.0-6388000.0-6387000.0-6387000.0-6387000.0-3944000.0-3944000.0-3944000.0-3944000.0-4195000.0-4196000.0-4194000.0-4196000.0
Percentage of OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax dei:LegalEntity

swx:SouthwestGasCorporation


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-8472000.0-8474000.0-7188000.0-7187000.0-7187000.0-7188000.0-4441000.0-4442000.0-4441000.0-4441000.0-6388000.0-6387000.0-6387000.0-6387000.0-3944000.0-3944000.0-3944000.0-3944000.0-4195000.0-4196000.0-4194000.0-4196000.0
Percentage of OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossTax

us-gaap:OtherComprehensiveIncomeLossTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value566000.0566000.0-3510000.0572000.0525000.0525000.0-3116000.0397000.0395000.0396000.0864000.0483000.0-482000.0-485000.0-1177000.0682000.0683000.0683000.0-778000.0688000.0690000.0688000.0
Percentage of OtherComprehensiveIncomeLossTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossTax dei:LegalEntity

swx:SouthwestGasCorporation


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value566000.0566000.0-3510000.0572000.0525000.0525000.0-3116000.0397000.0395000.0396000.0864000.0483000.0-482000.0-485000.0-2919000.0682000.0683000.0683000.0-3354000.0688000.0690000.0688000.0
Percentage of OtherComprehensiveIncomeLossTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0248.0100.0100.0100.0431.1100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossTax dei:LegalEntity, us-gaap:StatementEquityComponents

swx:SouthwestGasCorporation, swx:AccumulatedDefinedBenefitPlansAdjustmentRegulartoryAdjustmentAttributabletoParent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value-2298000.0-2298000.07829000.0-2014000.0-2015000.0-2015000.012717000.0-1283000.0-1283000.0-1284000.03467000.0
Percentage of OtherComprehensiveIncomeLossTax-406.0-406.0-223.0-352.1-383.8-383.8-408.1-323.2-324.8-324.2401.3

swx:SouthwestGasCorporation, us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value436000.0435000.0-3641000.0325000.0324000.0324000.0-3317000.0196000.0195000.0195000.0662000.0
Percentage of OtherComprehensiveIncomeLossTax77.076.9103.756.861.761.7106.549.449.449.276.6

swx:SouthwestGasCorporation, us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCredit


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value58000.058000.069000.070000.069000.069000.076000.077000.076000.076000.080000.0
Percentage of OtherComprehensiveIncomeLossTax10.210.2-2.012.213.113.1-2.419.419.219.29.3

swx:SouthwestGasCorporation, us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLoss


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value2676000.02675000.02270000.02269000.02270000.02270000.01403000.01402000.01402000.01403000.02017000.0
Percentage of OtherComprehensiveIncomeLossTax472.8472.6-64.7396.7432.4432.4-45.0353.1354.9354.3233.4

swx:SouthwestGasCorporation, us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value130000.0131000.0131000.0247000.0201000.0201000.0201000.0201000.0200000.0201000.0202000.0
Percentage of OtherComprehensiveIncomeLossTax23.023.1-3.743.238.338.3-6.550.650.650.823.4

us-gaap:OtherComprehensiveIncomeLossTax us-gaap:StatementEquityComponents

swx:AccumulatedDefinedBenefitPlansAdjustmentRegulartoryAdjustmentAttributabletoParent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value-2298000.0-2298000.07829000.0-2014000.0-2015000.0-2015000.012717000.0-1283000.0-1283000.0-1284000.03467000.0
Percentage of OtherComprehensiveIncomeLossTax-406.0-406.0-223.0-352.1-383.8-383.8-408.1-323.2-324.8-324.2401.3

us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value436000.0435000.0-3641000.0325000.0324000.0324000.0-3317000.0196000.0195000.0195000.0662000.0283000.0282000.0283000.0-1495000.0365000.0
Percentage of OtherComprehensiveIncomeLossTax77.076.9103.756.861.761.7106.549.449.449.276.658.6-58.5-58.4127.053.5

us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCredit


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value58000.058000.069000.070000.069000.069000.076000.077000.076000.076000.080000.0
Percentage of OtherComprehensiveIncomeLossTax10.210.2-2.012.213.113.1-2.419.419.219.29.3

us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLoss


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value2676000.02675000.02270000.02269000.02270000.02270000.01403000.01402000.01402000.01403000.02017000.0
Percentage of OtherComprehensiveIncomeLossTax472.8472.6-64.7396.7432.4432.4-45.0353.1354.9354.3233.4

us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value130000.0131000.0131000.0247000.0201000.0201000.0201000.0201000.0200000.0201000.0202000.0200000.0200000.0202000.0318000.0317000.0
Percentage of OtherComprehensiveIncomeLossTax23.023.1-3.743.238.338.3-6.550.650.650.823.441.4-41.5-41.6-27.046.5

us-gaap:PaymentsForProceedsFromOtherInvestingActivities

us-gaap:PaymentsForProceedsFromOtherInvestingActivities


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value-5596000.0-3563000.0-2483000.0-1475000.0-615000.0-4430000.0-2291000.0-11703000.0-897000.0-262000.0-514000.0-1263000.0
Percentage of PaymentsForProceedsFromOtherInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsForProceedsFromOtherInvestingActivities dei:LegalEntity

swx:SouthwestGasCorporation


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value-127000.0121000.0-588000.0-83000.0-131000.031000.044000.02000.0-29000.078000.01302000.0-538000.0
Percentage of PaymentsForProceedsFromOtherInvestingActivities2.3-3.423.75.621.3-0.7-1.9-0.03.2-29.8-253.342.6

us-gaap:PaymentsOfStockIssuanceCosts us-gaap:SubsidiarySaleOfStock

us-gaap:PaymentsOfStockIssuanceCosts

swx:EquityShelfProgram


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-03-312018-12-312018-03-312017-12-31
Value703600.0464480.0464260.0327890.0500000.0250000.0243380.0230730.0091997.0300000.0
Percentage of PaymentsOfStockIssuanceCosts100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0

us-gaap:PaymentsRelatedToTaxWithholdingForShareBasedCompensation

us-gaap:PaymentsRelatedToTaxWithholdingForShareBasedCompensation


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value1000.01242000.00002736000.002000.018000.01838000.0230000.026000.02000.02852000.0056000.0602000.02518000.00151000.070000.01898000.0
Percentage of PaymentsRelatedToTaxWithholdingForShareBasedCompensation100.0100.00.00.00.0100.00.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.0

us-gaap:PaymentsRelatedToTaxWithholdingForShareBasedCompensation dei:LegalEntity

swx:SouthwestGasCorporation


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value01242000.00002736000.01000.01000.018000.01838000.0230000.025000.03000.02852000.0056000.0602000.02518000.00151000.070000.01898000.0
Percentage of PaymentsRelatedToTaxWithholdingForShareBasedCompensation0.0100.00.00.00.0100.00.050.0100.0100.0100.096.2150.0100.00.0100.0100.0100.00.0100.0100.0100.0

us-gaap:PaymentsToAcquireBusinessesNetOfCashAcquired

us-gaap:PaymentsToAcquireBusinessesNetOfCashAcquired


Payments
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312016-09-30
Value0.00.250.0280.0190.02470.00.04.209940.00.0
Percentage of PaymentsToAcquireBusinessesNetOfCashAcquired0.0100.00.0100.00.0100.00.0100.00.00.0100.0100.00.00.0

us-gaap:ProceedsFromContributionsFromParent dei:LegalEntity

us-gaap:ProceedsFromContributionsFromParent

swx:SouthwestGasCorporation


Proceeds
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value694545324950332479222234560.029
Percentage of ProceedsFromContributionsFromParent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0

us-gaap:ProceedsFromIssuanceOfCommonStock

us-gaap:ProceedsFromIssuanceOfCommonStock


Proceeds
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302016-12-312016-09-302016-06-302016-03-31
Value72484835523.148282676252622357112911-0.0580.0430.0860.401
Percentage of ProceedsFromIssuanceOfCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromIssuanceOfCommonStock us-gaap:SubsidiarySaleOfStock

swx:EquityShelfProgram


Proceeds
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-03-312017-12-31
Value69454532490.0242474220.09.10766429
Percentage of ProceedsFromIssuanceOfCommonStock96.393.994.692.494.60.086.590.696.688.30.081.2100.4

us-gaap:ProceedsFromPaymentsForOtherFinancingActivities

us-gaap:ProceedsFromPaymentsForOtherFinancingActivities


Proceeds
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-270000.0-1353000.0-1957000.0-87000.0-1159000.0-199000.0-2443000.02133000.0-913000.0-53000.0-1623000.0-223000.0-561000.0-337000.0-1970000.0-68000.0-123000.0-913000.0-964000.0-481000.0-266000.0142000.0
Percentage of ProceedsFromPaymentsForOtherFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromPaymentsForOtherFinancingActivities dei:LegalEntity

swx:SouthwestGasCorporation


Proceeds
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-58000.0-205000.0-76000.0-23000.0-1048000.0-115000.0-24000.0-89000.0-659000.0-53000.0-89000.0-160000.0-481000.0-298000.0-52000.0-19000.0-2000.0-523000.0-964000.0-481000.0-266000.0142000.0
Percentage of ProceedsFromPaymentsForOtherFinancingActivities21.515.23.926.490.457.81.0-4.272.2100.05.571.785.788.42.627.91.657.3100.0100.0100.0100.0

us-gaap:PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity dei:LegalEntity, us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity

swx:SouthwestGasCorporation, us-gaap:OperatingSegments, swx:NaturalGasOperations


Public
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-981000.0981000.01311000.01232000.01120000.01061000.0982000.01212000.01007000.0960000.02593000.0448000.0357000.0229000.0219000.0968000.0
Percentage of PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedCostOfEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax dei:LegalEntity, us-gaap:StatementEquityComponents

us-gaap:ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax

swx:SouthwestGasCorporation, us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent


Reclassification
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value-0.544-0.544-0.544-1.03-0.836-0.837-0.836-0.836-0.836-0.836-0.836
Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax us-gaap:StatementEquityComponents

swx:AccumulatedDefinedBenefitPlansAdjustmentRegulartoryAdjustmentAttributabletoParent


Reclassification
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value9.5759.575-32.6198.3948.3958.395-52.9875.3485.3485.347-14.4467.567.5597.56-29.5445.734
Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax-1760.1-1760.15996.1-815.0-1004.2-1003.06338.2-639.7-639.7-639.61728.00.00.00.00.00.0

us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCredit


Reclassification
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-0.24-0.24-0.288-0.289-0.289-0.289-0.318-0.318-0.318-0.317-0.333-0.334-0.334-0.334-0.334-0.333
Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax44.144.152.928.134.634.538.038.038.037.939.80.00.00.00.00.0

us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLoss


Reclassification
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-11.148-11.149-9.458-9.457-9.457-9.458-5.844-5.844-5.844-5.844-8.405-8.404-8.404-8.404-6.361-6.362
Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax2049.32049.41738.6918.21131.21130.0699.0699.0699.0699.01005.40.00.00.00.00.0

us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent


Reclassification
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-0.544-0.544-0.544-1.03-0.836-0.837-0.836-0.836-0.836-0.836-0.836-0.836-0.836-0.837-0.837-0.835
Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.00.00.0

us-gaap:ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax dei:LegalEntity, us-gaap:StatementEquityComponents

us-gaap:ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax

swx:SouthwestGasCorporation, us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent


Reclassification
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value-0.414-0.413-0.413-0.783-0.635-0.636-0.635-0.635-0.636-0.635-0.634
Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax us-gaap:StatementEquityComponents

swx:AccumulatedDefinedBenefitPlansAdjustmentRegulartoryAdjustmentAttributabletoParent


Reclassification
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value7.2777.277-24.796.386.386.38-40.274.0654.0644.063-10.9795.7465.7445.746-23.2573.555
Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax-1757.7-1762.06002.4-814.8-1004.7-1003.16341.7-640.2-639.0-639.81731.70.00.00.00.00.0

us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCredit


Reclassification
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-0.182-0.182-0.219-0.22-0.22-0.22-0.242-0.241-0.242-0.241-0.253-0.254-0.254-0.254-0.207-0.207
Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax44.044.153.028.134.634.638.138.038.138.039.90.00.00.00.00.0

us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLoss


Reclassification
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-8.472-8.474-7.188-7.187-7.187-7.188-4.441-4.442-4.441-4.441-6.388-6.387-6.387-6.387-3.944-3.944
Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax2046.42051.81740.4917.91131.81130.2699.4699.5698.3699.41007.60.00.00.00.00.0

us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent


Reclassification
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-0.414-0.413-0.413-0.783-0.635-0.636-0.635-0.635-0.636-0.635-0.634-0.636-0.636-0.635-0.519-0.518
Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.00.00.0

us-gaap:ReclassificationFromAociCurrentPeriodTax dei:LegalEntity, us-gaap:StatementEquityComponents

us-gaap:ReclassificationFromAociCurrentPeriodTax

swx:SouthwestGasCorporation, us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent


Reclassification
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value-130000.0-131000.0-131000.0-247000.0-201000.0-201000.0-201000.0-201000.0-200000.0-201000.0-202000.0
Percentage of ReclassificationFromAociCurrentPeriodTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ReclassificationFromAociCurrentPeriodTax us-gaap:StatementEquityComponents

swx:AccumulatedDefinedBenefitPlansAdjustmentRegulartoryAdjustmentAttributabletoParent


Reclassification
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value2298000.02298000.0-7829000.02014000.02015000.02015000.0-12717000.01283000.01284000.01284000.0-3467000.01814000.01815000.01814000.0-6287000.02179000.0
Percentage of ReclassificationFromAociCurrentPeriodTax-1767.7-1754.25976.3-815.4-1002.5-1002.56326.9-638.3-642.0-638.81716.30.00.00.00.00.0

us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCredit


Reclassification
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-58000.0-58000.0-69000.0-69000.0-69000.0-69000.0-76000.0-77000.0-76000.0-76000.0-80000.0-80000.0-80000.0-80000.0-127000.0-126000.0
Percentage of ReclassificationFromAociCurrentPeriodTax44.644.352.727.934.334.337.838.338.037.839.60.00.00.00.00.0

us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLoss


Reclassification
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-2676000.0-2675000.0-2270000.0-2270000.0-2270000.0-2270000.0-1403000.0-1402000.0-1403000.0-1403000.0-2017000.0-2017000.0-2017000.0-2017000.0-2417000.0-2418000.0
Percentage of ReclassificationFromAociCurrentPeriodTax2058.52042.01732.8919.01129.41129.4698.0697.5701.5698.0998.50.00.00.00.00.0

us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent


Reclassification
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-130000.0-131000.0-131000.0-247000.0-201000.0-201000.0-201000.0-201000.0-200000.0-201000.0-202000.0-200000.0-200000.0-202000.0-318000.0-317000.0
Percentage of ReclassificationFromAociCurrentPeriodTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.00.00.0

us-gaap:RegulatedOperatingRevenueGas

us-gaap:RegulatedOperatingRevenueGas


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value292521374210262502379209258520370217275494366213260462340200255525
Percentage of RegulatedOperatingRevenueGas100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RegulatedOperatingRevenueGas dei:LegalEntity

swx:SouthwestGasCorporation


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value292521374210262502379209258520370217275494366213260462340200255525
Percentage of RegulatedOperatingRevenueGas100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod us-gaap:PlanName

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod

swx:DividendReinvestmentAndStockPurchasePlan


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value41500.049500.042000.044000.039000.047000.051000.029000.033000.034000.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

swx:RestrictedStockUnitPlanAndManagementIncentivePlan


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value047000.00024000.072000.01000.0023000.053000.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod0.094.90.00.061.5153.22.00.069.7155.9

us-gaap:StockIssuedDuringPeriodSharesNewIssues us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodSharesNewIssues

us-gaap:CommonStock


Stock
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value1093000.0802000.0734000.0549000.0784000.0119000.0383000.0303000.0930000.0365000.03603000.0297000.0789000.0247000.0358000.0149000.034000.067000.0
Percentage of StockIssuedDuringPeriodSharesNewIssues100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StockIssuedDuringPeriodValueShareBasedCompensation dei:LegalEntity, us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodValueShareBasedCompensation

swx:SouthwestGasCorporation, us-gaap:AdditionalPaidInCapital


Stock
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value1.4182.0150.9431.1371.1350.1250.5881.1021.2970.9181.0271.1971.27-0.5681.4861.2071.4635.906
Percentage of StockIssuedDuringPeriodValueShareBasedCompensation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

swx:SouthwestGasCorporation, us-gaap:RetainedEarnings


Stock
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-0.167-0.35-0.139-0.139-0.138-0.364-0.153-0.153-0.152-0.16-0.17-0.172-0.172-0.166-0.197-0.195-0.197-0.195
Percentage of StockIssuedDuringPeriodValueShareBasedCompensation-11.8-17.4-14.7-12.2-12.2-291.2-26.0-13.9-11.7-17.4-16.6-14.4-13.529.2-13.3-16.2-13.5-3.3

us-gaap:TaxesExcludingIncomeAndExciseTaxes

us-gaap:TaxesExcludingIncomeAndExciseTaxes


Taxes
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value19201515151615151516141514151414141412121214
Percentage of TaxesExcludingIncomeAndExciseTaxes100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:TaxesExcludingIncomeAndExciseTaxes dei:LegalEntity

swx:SouthwestGasCorporation


Taxes
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value19201515151615151516141514151414141412121214
Percentage of TaxesExcludingIncomeAndExciseTaxes100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:UtilitiesOperatingExpenseGasAndPetroleumPurchased

us-gaap:UtilitiesOperatingExpenseGasAndPetroleumPurchased


Utilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value761567836671609235651921004983185934569146733971213
Percentage of UtilitiesOperatingExpenseGasAndPetroleumPurchased100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:UtilitiesOperatingExpenseGasAndPetroleumPurchased dei:LegalEntity

swx:SouthwestGasCorporation


Utilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value761567836671609235651921004983185934569146733971213
Percentage of UtilitiesOperatingExpenseGasAndPetroleumPurchased100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:UtilitiesOperatingExpenseMaintenanceAndOperations

us-gaap:UtilitiesOperatingExpenseMaintenanceAndOperations


Utilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value1041061031019910310210910510693105105102971021031099910298100
Percentage of UtilitiesOperatingExpenseMaintenanceAndOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:UtilitiesOperatingExpenseMaintenanceAndOperations dei:LegalEntity

swx:SouthwestGasCorporation


Utilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value1031061021019910310210910410592104105102971021021089910298100
Percentage of UtilitiesOperatingExpenseMaintenanceAndOperations98.499.599.799.499.999.399.799.499.799.399.699.299.899.899.699.999.599.6100.0100.0100.0100.0

swx:AccruedPropertyTaxes

swx:AccruedPropertyTaxes


Accrued
Period End2021-03-312020-12-31
Value3725
Percentage of AccruedPropertyTaxes100.0100.0

swx:AccruedUtilityRevenue

swx:AccruedUtilityRevenue


Accrued
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value3850823635487935344777343447783433457674
Percentage of AccruedUtilityRevenue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

swx:AccruedUtilityRevenue dei:LegalEntity

swx:SouthwestGasCorporation


Accrued
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value38508236354879353447773434477834334576
Percentage of AccruedUtilityRevenue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

swx:BilledOnCompletedContractsAndContractsInProgress

swx:BilledOnCompletedContractsAndContractsInProgress


Billed
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value271235169216238207159184219
Percentage of BilledOnCompletedContractsAndContractsInProgress100.0100.0100.0100.0100.0100.0100.0100.0100.0

swx:DebtInstrumentPercentageOfTotalWithInterestRatesReferenceToLIBORAndDueAfter2021

swx:DebtInstrumentPercentageOfTotalWithInterestRatesReferenceToLIBORAndDueAfter2021


Debt
Period End2020-09-302020-03-312019-12-312019-09-302019-06-30
Value8.00.180.190.140.11
Percentage of DebtInstrumentPercentageOfTotalWithInterestRatesReferenceToLIBORAndDueAfter2021100.0100.0100.0100.0100.0

swx:DebtInstrumentPercentageOfTotalWithInterestRatesReferenceToLIBORAndDueAfter2021 dei:LegalEntity

swx:SouthwestGasCorporation


Debt
Period End2020-09-302020-03-312019-12-312019-09-302019-06-30
Value0.30.110.130.060.02
Percentage of DebtInstrumentPercentageOfTotalWithInterestRatesReferenceToLIBORAndDueAfter20213.861.168.442.918.2

swx:DebtInstrumentUnamortizedDiscountAndDebtIssuanceCosts dei:LegalEntity, us-gaap:DebtInstrument, us-gaap:FairValueByMeasurementBasis

swx:DebtInstrumentUnamortizedDiscountAndDebtIssuanceCosts

swx:SouthwestGasCorporation, swx:Debentures, us-gaap:CarryingReportedAmountFairValueDisclosure


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value17171718181414141511111212129.359.4989.6449.7889.931
Percentage of DebtInstrumentUnamortizedDiscountAndDebtIssuanceCosts100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

swx:SouthwestGasCorporation, swx:IndustrialDevelopmentRevenueBonds, us-gaap:CarryingReportedAmountFairValueDisclosure


Debt
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-31
Value1.3491.4111.4721.5331.5941.6561.7171.7781.8391.92.0241.8421.9342.0262.1192.489
Percentage of DebtInstrumentUnamortizedDiscountAndDebtIssuanceCosts7.88.18.38.58.611.611.912.012.216.317.115.315.816.222.725.1

swx:DeferredIncomeTaxesAndUnamortizedInvestmentTaxCredits

swx:DeferredIncomeTaxesAndUnamortizedInvestmentTaxCredits


Deferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value694671647639631624599577563556529519510500476894891879840769
Percentage of DeferredIncomeTaxesAndUnamortizedInvestmentTaxCredits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

swx:DeferredIncomeTaxesAndUnamortizedInvestmentTaxCredits dei:LegalEntity

swx:SouthwestGasCorporation


Deferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value620596581566558547539527519517490485473464445853855846806
Percentage of DeferredIncomeTaxesAndUnamortizedInvestmentTaxCredits89.388.889.888.688.487.689.991.392.293.092.793.492.892.893.495.596.096.395.9

swx:DeferredTaxAssetsLeaseRelatedItem

swx:DeferredTaxAssetsLeaseRelatedItem


Deferred
Period End2020-12-312019-12-312018-12-31
Value20210.0
Percentage of DeferredTaxAssetsLeaseRelatedItem100.0100.00.0

swx:DeferredTaxLiabilitiesLeaseRelatedItem

swx:DeferredTaxLiabilitiesLeaseRelatedItem


Deferred
Period End2020-12-312019-12-312018-12-31
Value19200.0
Percentage of DeferredTaxLiabilitiesLeaseRelatedItem100.0100.00.0

swx:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeLossAmountRecognizedRegulatoryAssetsBeforeTax

swx:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeLossAmountRecognizedRegulatoryAssetsBeforeTax


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-408400000.0-417980000.0-427550000.0-394930000.0-403320000.0-411720000.0-420110000.0-367130000.0-372480000.0-377820000.0-383170000.0-368720000.0-391400000.0
Percentage of DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeLossAmountRecognizedRegulatoryAssetsBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

swx:FutureEstimatedFundingAmountInNextFiscalYear

swx:FutureEstimatedFundingAmountInNextFiscalYear


Future
Period End2020-12-31
Value105
Percentage of FutureEstimatedFundingAmountInNextFiscalYear100.0

swx:FutureEstimatedFundingAmountInNextFiscalYear us-gaap:RetirementPlanType

us-gaap:OtherPensionPlansDefinedBenefit


Future
Period End2020-12-31
Value102
Percentage of FutureEstimatedFundingAmountInNextFiscalYear97.1

swx:IncomeTaxesPayableNet

swx:IncomeTaxesPayableNet


Income
Period End2020-12-312019-12-312018-12-312018-03-312017-12-312017-09-302016-12-312015-12-31
Value122.0691.083125.9461.5431.9090.94
Percentage of IncomeTaxesPayableNet100.0100.0100.0100.0100.0100.0100.0100.0

swx:MaximumAmountOfCommonStockAvailableForSale us-gaap:SubsidiarySaleOfStock

swx:MaximumAmountOfCommonStockAvailableForSale

swx:EquityShelfProgram


Maximum
Period End2020-12-31
Value46
Percentage of MaximumAmountOfCommonStockAvailableForSale100.0

swx:NetRegulatoryLiabilities

swx:NetRegulatoryLiabilities


Net
Period End2020-12-312019-12-312018-12-31
Value406363376
Percentage of NetRegulatoryLiabilities100.0100.0100.0

swx:OperatingLossCarryforwardsNetOfFederalBenefit us-gaap:IncomeTaxAuthority

swx:OperatingLossCarryforwardsNetOfFederalBenefit

us-gaap:StateAndLocalJurisdiction


Operating
Period End2020-12-31
Value3200000.0
Percentage of OperatingLossCarryforwardsNetOfFederalBenefit100.0

swx:OtherPropertyAndInvestments

swx:OtherPropertyAndInvestments


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value860842834825809785784768761716623466462442428369362351342313
Percentage of OtherPropertyAndInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

swx:OtherPropertyAndInvestments dei:LegalEntity

swx:SouthwestGasCorporation


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value149146143135130118133127127123116125120118119115113111108
Percentage of OtherPropertyAndInvestments17.417.417.216.516.115.117.116.616.717.318.626.826.126.827.831.431.231.731.7

swx:PropertyPlantEquipmentAndIntangibleAssetsGross dei:LegalEntity

swx:PropertyPlantEquipmentAndIntangibleAssetsGross

swx:CenturiGroupInc.


Property
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value113911061089107310411009983968952894792
Percentage of PropertyPlantEquipmentAndIntangibleAssetsGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

swx:PublicUtilitiesPropertyPlantAndEquipmentGasPlant

swx:PublicUtilitiesPropertyPlantAndEquipmentGasPlant


Public
Period End2021-06-302020-12-31
Value86648384
Percentage of PublicUtilitiesPropertyPlantAndEquipmentGasPlant100.0100.0

swx:PublicUtilitiesPropertyPlantAndEquipmentGasPlant dei:LegalEntity

swx:SouthwestGasCorporation


Public
Period End2021-06-302020-12-31
Value86648384
Percentage of PublicUtilitiesPropertyPlantAndEquipmentGasPlant100.0100.0

swx:PublicUtilitiesPropertyPlantandEquipmentGasPlant

swx:PublicUtilitiesPropertyPlantandEquipmentGasPlant


Public
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312018-12-31
Value8479838482198086794978137134
Percentage of PublicUtilitiesPropertyPlantandEquipmentGasPlant100.0100.0100.0100.0100.0100.0100.0

swx:PublicUtilitiesPropertyPlantandEquipmentGasPlant dei:LegalEntity

swx:SouthwestGasCorporation


Public
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312018-12-31
Value8479838482198086794978137134
Percentage of PublicUtilitiesPropertyPlantandEquipmentGasPlant100.0100.0100.0100.0100.0100.0100.0

swx:PublicUtilitiesPropertyPlantandEquipmentGasPlant us-gaap:FiniteLivedIntangibleAssetsByMajorClass

us-gaap:ComputerSoftwareIntangibleAsset


Public
Period End2020-12-312019-12-312018-12-31
Value270256241
Percentage of PublicUtilitiesPropertyPlantandEquipmentGasPlant3.23.33.4

swx:PublicUtilitiesPropertyPlantandEquipmentGasPlant us-gaap:PublicUtility

swx:General


Public
Period End2020-12-312019-12-312018-12-31
Value515467416
Percentage of PublicUtilitiesPropertyPlantandEquipmentGasPlant6.26.05.8

swx:Storage


Public
Period End2020-12-312019-12-312018-12-31
Value10110026
Percentage of PublicUtilitiesPropertyPlantandEquipmentGasPlant1.21.30.4

us-gaap:GasDistribution


Public
Period End2020-12-312019-12-312018-12-31
Value707865816049
Percentage of PublicUtilitiesPropertyPlantandEquipmentGasPlant84.484.284.8

us-gaap:GasTransmission


Public
Period End2020-12-312019-12-312018-12-31
Value400391386
Percentage of PublicUtilitiesPropertyPlantandEquipmentGasPlant4.85.05.4

us-gaap:OtherPlantInService


Public
Period End2020-12-312019-12-312018-12-31
Value161514
Percentage of PublicUtilitiesPropertyPlantandEquipmentGasPlant0.20.20.2

swx:SaleOfStockCommonStockAvailableForSale us-gaap:SubsidiarySaleOfStock

swx:SaleOfStockCommonStockAvailableForSale

swx:EquityShelfProgram


Sale
Period End2020-09-30
Value92
Percentage of SaleOfStockCommonStockAvailableForSale100.0

swx:StockholdersEquityAttributableToParentBeforeTax dei:LegalEntity, us-gaap:StatementEquityComponents

swx:StockholdersEquityAttributableToParentBeforeTax

swx:SouthwestGasCorporation, us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-74093000.0-75906000.0-77720000.0-62546000.0-63898000.0-65249000.0-66601000.0-52785000.0-53599000.0-54413000.0-55227000.0-57985000.0-61520000.0
Percentage of StockholdersEquityAttributableToParentBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

swx:SouthwestGasCorporation, us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-1631000.0-2175000.0-2719000.0-3263000.0-4293000.0-5129000.0-5966000.0-6802000.0-7638000.0-8474000.0-9310000.0-10146000.0-12655000.0
Percentage of StockholdersEquityAttributableToParentBeforeTax2.22.93.55.26.77.99.012.914.315.616.917.520.6

swx:StockholdersEquityAttributableToParentTax dei:LegalEntity, us-gaap:StatementEquityComponents

swx:StockholdersEquityAttributableToParentTax

swx:SouthwestGasCorporation, us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value17181815151515121213202122
Percentage of StockholdersEquityAttributableToParentTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

swx:SouthwestGasCorporation, us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value0.390.520.6510.7821.0291.231.4311.6321.8332.0334.0054.2074.809
Percentage of StockholdersEquityAttributableToParentTax2.22.93.55.26.77.99.012.914.215.619.319.621.6

swx:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestBeforeTax us-gaap:StatementEquityComponents

swx:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestBeforeTax

us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-74093000.0-75906000.0-77720000.0-62546000.0-63898000.0-65249000.0-66601000.0-52785000.0-53599000.0-54413000.0-55227000.0-57985000.0-61520000.0
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterest


Stockholders
Period End2021-06-302021-03-312020-12-312019-12-312018-12-312017-12-31
Value1864000.0955000.0132000.0-1581000.0-3619000.0-609000.0
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestBeforeTax-2.5-1.3-0.22.46.61.0

us-gaap:AccumulatedTranslationAdjustment


Stockholders
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-2768000.0-3792000.0-5586000.0-1581000.0-2488000.0-2041000.0-2828000.0-3619000.0-1611000.0-609000.0
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestBeforeTax4.45.98.62.44.73.85.26.62.81.0

us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-1631000.0-2175000.0-2719000.0-3263000.0-4293000.0-5129000.0-5966000.0-6802000.0-7638000.0-8474000.0-9310000.0-10146000.0-12655000.0
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestBeforeTax2.22.93.55.26.77.99.012.914.315.616.917.520.6

swx:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestTax us-gaap:StatementEquityComponents

swx:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestTax

us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value17181815151515121213202122
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AociDerivativeQualifyingAsHedgeExcludedComponentParent


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value0.390.520.6510.7821.0291.231.4311.6321.8332.0334.0054.2074.809
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestTax2.22.93.55.26.77.99.012.914.215.619.319.621.6

us-gaap:AccountsReceivableGross

us-gaap:AccountsReceivableGross


Accounts
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value277241174224239208161186221
Percentage of AccountsReceivableGross100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccountsReceivableNet

us-gaap:AccountsReceivableNet


Accounts
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value275240174223238205160186191187130221
Percentage of AccountsReceivableNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccrualForTaxesOtherThanIncomeTaxesCurrent

us-gaap:AccrualForTaxesOtherThanIncomeTaxesCurrent


Accrual
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value5172485948734852426943514263434840624247
Percentage of AccrualForTaxesOtherThanIncomeTaxesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccrualForTaxesOtherThanIncomeTaxesCurrent dei:LegalEntity

swx:SouthwestGasCorporation


Accrual
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value51724859487348524269435142634348406242
Percentage of AccrualForTaxesOtherThanIncomeTaxesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AllowanceForDoubtfulAccountsReceivable

us-gaap:AllowanceForDoubtfulAccountsReceivable


Allowance
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value4334000.01488000.0443000.0439000.0820000.0595000.03349000.0383000.0439000.061000.0
Percentage of AllowanceForDoubtfulAccountsReceivable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AssetsNoncurrentOtherThanNoncurrentInvestmentsAndPropertyPlantAndEquipment

us-gaap:AssetsNoncurrentOtherThanNoncurrentInvestmentsAndPropertyPlantAndEquipment


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302016-12-31
Value836844854816813824840770782806801597601616628560561573
Percentage of AssetsNoncurrentOtherThanNoncurrentInvestmentsAndPropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AssetsNoncurrentOtherThanNoncurrentInvestmentsAndPropertyPlantAndEquipment dei:LegalEntity

swx:SouthwestGasCorporation


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302016-12-31
Value4814915004654644664734204274334354134204284354044091000
Percentage of AssetsNoncurrentOtherThanNoncurrentInvestmentsAndPropertyPlantAndEquipment57.658.258.657.057.156.656.354.654.653.754.369.370.069.669.372.073.0174.4

us-gaap:CapitalizationLongtermDebtAndEquity

us-gaap:CapitalizationLongtermDebtAndEquity


Capitalization
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value55265675557254125337494248904970487545354440406939703874361034453420330032333159
Percentage of CapitalizationLongtermDebtAndEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CapitalizationLongtermDebtAndEquity dei:LegalEntity

swx:SouthwestGasCorporation


Capitalization
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value4593478746714490443941053996404539593706360135383435338631313051300429353058
Percentage of CapitalizationLongtermDebtAndEquity83.184.483.883.083.283.181.781.481.281.781.187.086.587.486.788.687.888.994.6

us-gaap:CashAndCashEquivalentsFairValueDisclosure dei:LegalEntity, us-gaap:CashAndCashEquivalents

us-gaap:CashAndCashEquivalentsFairValueDisclosure

swx:SouthwestGasCorporation, us-gaap:MoneyMarketFunds


Cash
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312018-12-312017-12-31
Value0.040.040.040.040.04231820
Percentage of CashAndCashEquivalentsFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CashAndCashEquivalentsFairValueDisclosure us-gaap:CashAndCashEquivalents

us-gaap:MoneyMarketFunds


Cash
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312018-12-312017-12-31
Value0.040.040.040.040.049265922
Percentage of CashAndCashEquivalentsFairValueDisclosure100.0100.0100.0100.0122.5113.6332.8106.7

us-gaap:CashSurrenderValueOfLifeInsurance dei:LegalEntity

us-gaap:CashSurrenderValueOfLifeInsurance

swx:SouthwestGasCorporation


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-31
Value146143140133128116132126125122114123118116117106
Percentage of CashSurrenderValueOfLifeInsurance100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CommonStockCapitalSharesReservedForFutureIssuance

us-gaap:CommonStockCapitalSharesReservedForFutureIssuance


Common
Period End2020-12-312019-12-312019-09-202019-09-192019-06-302019-05-022019-03-31
Value4.54.2120606012060
Percentage of CommonStockCapitalSharesReservedForFutureIssuance100.0100.0100.0100.0100.0100.0100.0

us-gaap:ContractWithCustomerAssetAccumulatedAllowanceForCreditLoss

us-gaap:ContractWithCustomerAssetAccumulatedAllowanceForCreditLoss


Contract
Period End2021-06-302021-03-312020-12-312019-12-31
Value2451000.01474000.02154000.0820000.0
Percentage of ContractWithCustomerAssetAccumulatedAllowanceForCreditLoss100.0100.0100.0100.0

us-gaap:ContractWithCustomerAssetGross

us-gaap:ContractWithCustomerAssetGross


Contract
Period End2021-06-302021-03-312020-12-312019-12-31
Value266198280224
Percentage of ContractWithCustomerAssetGross100.0100.0100.0100.0

us-gaap:ContractWithCustomerAssetGross us-gaap:AccountsNotesLoansAndFinancingReceivableByReceivableType

swx:BilledOnCompletedContractsAndContractsInProgress


Contract
Period End2021-06-302021-03-312020-12-312019-12-31
Value260193273216
Percentage of ContractWithCustomerAssetGross98.097.197.696.2

swx:OtherReceivables


Contract
Period End2021-06-302021-03-312020-12-312019-12-31
Value5.2855.7896.6928.456
Percentage of ContractWithCustomerAssetGross2.02.92.43.8

us-gaap:ContractWithCustomerAssetNet

us-gaap:ContractWithCustomerAssetNet


Contract
Period End2021-06-302021-03-312020-12-312019-12-312018-12-312017-12-31
Value26319727899875.768
Percentage of ContractWithCustomerAssetNet100.0100.0100.0100.0100.0100.0

us-gaap:ContractWithCustomerLiability

us-gaap:ContractWithCustomerLiability


Contract
Period End2021-06-302021-03-312020-12-312019-12-312018-12-312017-12-31
Value9077000.05985000.04507000.04525000.04211000.09602000.0
Percentage of ContractWithCustomerLiability100.0100.0100.0100.0100.0100.0

us-gaap:DebtInstrumentCollateralAmount dei:LegalEntity, us-gaap:LongtermDebtType

us-gaap:DebtInstrumentCollateralAmount

swx:CenturiGroupInc., swx:SecuredRevolvingCreditAndTermLoanFacility


Debt
Period End2021-06-302021-03-312020-09-30
Value140013001400
Percentage of DebtInstrumentCollateralAmount100.0100.0100.0

swx:CenturiGroupInc., swx:SecuredRevolvingCreditFacilityTermLoan


Debt
Period End2020-12-31
Value1400
Percentage of DebtInstrumentCollateralAmount0.0

us-gaap:DebtInstrumentInterestRateEffectivePercentage dei:LegalEntity, us-gaap:DebtInstrument

us-gaap:DebtInstrumentInterestRateEffectivePercentage

swx:SouthwestGasCorporation, swx:A250MillionTermLoan


Debt
Period End2021-06-302021-03-31
Value0.750.77
Percentage of DebtInstrumentInterestRateEffectivePercentage100.0100.0

us-gaap:DebtInstrumentInterestRateEffectivePercentage dei:LegalEntity, us-gaap:LongtermDebtType

swx:CenturiGroupInc., swx:SecuredRevolvingCreditFacilityTermLoan


Debt
Period End2020-12-312019-12-31
Value1.30.032
Percentage of DebtInstrumentInterestRateEffectivePercentage0.00.0

swx:SouthwestGasCorporation, swx:SouthwestGasCreditFacility


Debt
Period End2020-12-312019-12-312018-12-31
Value0.920.02570.0341
Percentage of DebtInstrumentInterestRateEffectivePercentage0.00.00.0

us-gaap:DebtInstrumentInterestRateEffectivePercentage us-gaap:LongtermDebtType

swx:VariableRateBondsTaxExemptSeriesADueTwoThousandAndTwentyEight


Debt
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value0.870.02320.02530.02560.01510.0081
Percentage of DebtInstrumentInterestRateEffectivePercentage0.00.00.00.00.00.0

swx:VariableRateBondsTwoThousandAndEightSeriesADueTwoThousandAndThirtyEight


Debt
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value0.830.02460.02520.02590.01530.0087
Percentage of DebtInstrumentInterestRateEffectivePercentage0.00.00.00.00.00.0

swx:VariableRateBondsTwoThousandAndNineSeriesADueTwoThousandAndThirtyNine


Debt
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value0.760.02370.02510.0240.01430.0075
Percentage of DebtInstrumentInterestRateEffectivePercentage0.00.00.00.00.00.0

swx:VariableRateBondsTwoThousandAndThreeSeriesADueTwoThousandAndThirtyEight


Debt
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value0.80.02510.02610.02440.01470.0087
Percentage of DebtInstrumentInterestRateEffectivePercentage0.00.00.00.00.00.0

us-gaap:DebtWeightedAverageInterestRate dei:LegalEntity, us-gaap:CreditFacility

us-gaap:DebtWeightedAverageInterestRate

swx:SouthwestGasCorporation, swx:A400MillionCreditFacility


Debt
Period End2020-12-312019-12-312018-12-31
Value1.10.02610.0347
Percentage of DebtWeightedAverageInterestRate100.0100.0100.0

us-gaap:DebtWeightedAverageInterestRate us-gaap:CreditFacility

swx:A100MillionCreditFacility


Debt
Period End2020-12-312019-12-31
Value1.2252.749
Percentage of DebtWeightedAverageInterestRate111.410532.6

us-gaap:DeferredCreditsAndOtherLiabilitiesNoncurrent

us-gaap:DeferredCreditsAndOtherLiabilitiesNoncurrent


Deferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value113611381199113811381146120411171112111810661031101210321018547553565570591
Percentage of DeferredCreditsAndOtherLiabilitiesNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredCreditsAndOtherLiabilitiesNoncurrent dei:LegalEntity

swx:SouthwestGasCorporation


Deferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value9829871043998100210141073100910151019102310029851003990522529539545
Percentage of DeferredCreditsAndOtherLiabilitiesNoncurrent86.486.787.087.788.188.589.190.391.391.196.097.297.397.197.395.595.595.395.6

us-gaap:DeferredGasCost

us-gaap:DeferredGasCost


Deferred
Period End2021-06-302021-03-312020-12-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value2352382.0530.00.0444958654.9280.018146.235.9569.1422.6083.591
Percentage of DeferredGasCost100.0100.0100.00.00.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredGasCost dei:LegalEntity

swx:SouthwestGasCorporation


Deferred
Period End2021-06-302021-03-312020-12-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value2352382.0530.00.0444958654.9280.018146.235.9569.1422.608
Percentage of DeferredGasCost100.0100.0100.00.00.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredGasPurchasesCurrent

us-gaap:DeferredGasPurchasesCurrent


Deferred
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value54766926608889727993260.3716.8411420279045
Percentage of DeferredGasPurchasesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredGasPurchasesCurrent dei:LegalEntity

swx:SouthwestGasCorporation


Deferred
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value54766926608889727993260.3716.84114202790
Percentage of DeferredGasPurchasesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredIncomeTaxAssetsNet

us-gaap:DeferredIncomeTaxAssetsNet


Deferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value345000.0563000.0455000.0841000.0632000.0765000.0856000.0896000.01021000.01074000.01264000.01185000.01480000.0
Percentage of DeferredIncomeTaxAssetsNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredIncomeTaxLiabilities

us-gaap:DeferredIncomeTaxLiabilities


Deferred
Period End2020-12-312019-12-31
Value839796
Percentage of DeferredIncomeTaxLiabilities100.0100.0

us-gaap:DeferredIncomeTaxLiabilities dei:LegalEntity

swx:SouthwestGasCorporation


Deferred
Period End2020-12-312019-12-31
Value699674
Percentage of DeferredIncomeTaxLiabilities83.384.7

us-gaap:DeferredTaxAssetsOperatingLossCarryforwards

us-gaap:DeferredTaxAssetsOperatingLossCarryforwards


Deferred
Period End2020-12-312019-12-31
Value4118000.07467000.0
Percentage of DeferredTaxAssetsOperatingLossCarryforwards100.0100.0

us-gaap:DeferredTaxAssetsOther

us-gaap:DeferredTaxAssetsOther


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value142017131824
Percentage of DeferredTaxAssetsOther100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsOther dei:LegalEntity

swx:SouthwestGasCorporation


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value7.79109.3868.8215
Percentage of DeferredTaxAssetsOther54.353.554.563.682.6

us-gaap:DeferredTaxAssetsTaxCreditCarryforwards

us-gaap:DeferredTaxAssetsTaxCreditCarryforwards


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value104105105981.0941.614
Percentage of DeferredTaxAssetsTaxCreditCarryforwards100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsTaxCreditCarryforwards dei:LegalEntity

swx:SouthwestGasCorporation


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value104105105981.094
Percentage of DeferredTaxAssetsTaxCreditCarryforwards100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value393739313836
Percentage of DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits dei:LegalEntity

swx:SouthwestGasCorporation


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value4.80613171822
Percentage of DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits12.036.344.259.758.7

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation


Deferred
Period End2020-12-31
Value9055000.0
Percentage of DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation100.0

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation dei:LegalEntity

swx:SouthwestGasCorporation


Deferred
Period End2020-12-31
Value1810000.0
Percentage of DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation20.0

us-gaap:DeferredTaxLiabilitiesDeferredExpenseDeferredFinancingCosts

us-gaap:DeferredTaxLiabilitiesDeferredExpenseDeferredFinancingCosts


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value2585000.02818000.03110000.03380000.05712000.05497000.0
Percentage of DeferredTaxLiabilitiesDeferredExpenseDeferredFinancingCosts100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilitiesDeferredExpenseDeferredFinancingCosts dei:LegalEntity

swx:SouthwestGasCorporation


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value2585000.02818000.03110000.03380000.05712000.0
Percentage of DeferredTaxLiabilitiesDeferredExpenseDeferredFinancingCosts100.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets

us-gaap:DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value13107.8077.6568.8039.547
Percentage of DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilitiesOther

us-gaap:DeferredTaxLiabilitiesOther


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value131930211931
Percentage of DeferredTaxLiabilitiesOther100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilitiesOther dei:LegalEntity

swx:SouthwestGasCorporation


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value1217271716
Percentage of DeferredTaxLiabilitiesOther92.289.390.980.884.3

us-gaap:DeferredTaxLiabilitiesPropertyPlantAndEquipment

us-gaap:DeferredTaxLiabilitiesPropertyPlantAndEquipment


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value785732678598872794
Percentage of DeferredTaxLiabilitiesPropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilitiesPropertyPlantAndEquipment dei:LegalEntity

swx:SouthwestGasCorporation


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value680644614561830
Percentage of DeferredTaxLiabilitiesPropertyPlantAndEquipment86.687.990.593.895.3

us-gaap:DeferredTaxLiabilitiesRegulatoryAssetsAndLiabilities

us-gaap:DeferredTaxLiabilitiesRegulatoryAssetsAndLiabilities


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value4205000.09931000.06097000.06067000.01104000.0743000.0
Percentage of DeferredTaxLiabilitiesRegulatoryAssetsAndLiabilities100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilitiesRegulatoryAssetsAndLiabilities dei:LegalEntity

swx:SouthwestGasCorporation


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value4205000.09931000.06097000.06067000.01104000.0
Percentage of DeferredTaxLiabilitiesRegulatoryAssetsAndLiabilities100.0100.0100.0100.0100.0

us-gaap:DefinedBenefitPlanAccumulatedBenefitObligation us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanAccumulatedBenefitObligation

us-gaap:OtherPensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value1367121910241088939
Percentage of DefinedBenefitPlanAccumulatedBenefitObligation100.0100.0100.0100.0100.0

us-gaap:SupplementalEmployeeRetirementPlanDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value5046384440
Percentage of DefinedBenefitPlanAccumulatedBenefitObligation3.73.83.84.14.4

us-gaap:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax

us-gaap:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value-74.093-75.906-77.72-62.546-63.898-65.249-66.601-52.785-53.599-54.413-55.227-57.9855960615455565757
Percentage of DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax

us-gaap:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value480491502454464473483417423429435423448
Percentage of DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax

us-gaap:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value-2007000.0-2247000.0-2487000.0-2774000.0-3063000.0-3352000.0-3641000.0-2080000.0-2398000.0-2716000.0-3033000.0-3366000.0-4368000.0
Percentage of DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate

us-gaap:OtherPensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value2.750.0350.0450.03750.045
Percentage of DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate100.0100.0100.0100.0100.0

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value2.750.0350.0450.03750.045
Percentage of DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate100.0100.0100.0100.0100.0

us-gaap:SupplementalEmployeeRetirementPlanDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value2.750.0350.0450.03750.045
Percentage of DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate100.0100.0100.0100.0100.0

us-gaap:DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease

us-gaap:OtherPensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value3.00.03250.03250.03250.0325
Percentage of DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease100.0100.0100.0100.0100.0

us-gaap:SupplementalEmployeeRetirementPlanDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value3.00.03250.03250.03250.0325
Percentage of DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease100.0100.0100.0100.0100.0

us-gaap:DefinedBenefitPlanBenefitObligation us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanBenefitObligation

us-gaap:OtherPensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value149913291116120310481044
Percentage of DefinedBenefitPlanBenefitObligation100.0100.0100.0100.0100.0100.0

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value827669757372
Percentage of DefinedBenefitPlanBenefitObligation5.55.76.36.37.07.0

us-gaap:SupplementalEmployeeRetirementPlanDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value534740454342
Percentage of DefinedBenefitPlanBenefitObligation3.63.63.63.84.14.1

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value24222019
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter100.0100.0100.0100.0

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value339331319308
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter1412.51471.11526.31573.0

us-gaap:SupplementalEmployeeRetirementPlanDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value15141314
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter62.965.865.171.9

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value4.94.94.54.1
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths100.0100.0100.0100.0

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value58565451
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths1183.71142.91200.01243.9

us-gaap:SupplementalEmployeeRetirementPlanDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value3.23.13.03.0
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths65.363.366.773.2

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value4.94.84.54.2
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive100.0100.0100.0100.0

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value63615956
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive1285.71270.81311.11347.6

us-gaap:SupplementalEmployeeRetirementPlanDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value3.13.12.82.9
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive63.364.662.269.0

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value4.94.94.64.3
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour100.0100.0100.0100.0

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value62605855
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour1265.31224.51260.91281.4

us-gaap:SupplementalEmployeeRetirementPlanDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value3.23.12.92.9
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour65.363.363.067.4

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value4.94.94.64.3
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree100.0100.0100.0100.0

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value61595653
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree1244.91204.11217.41246.5

us-gaap:SupplementalEmployeeRetirementPlanDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value3.23.12.93.0
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree65.363.363.069.8

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value5.04.94.64.2
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo100.0100.0100.0100.0

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value60585552
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo1200.01183.71195.71242.9

us-gaap:SupplementalEmployeeRetirementPlanDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value3.23.12.93.0
Percentage of DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo64.063.363.071.4

us-gaap:DefinedBenefitPlanFairValueOfPlanAssets

us-gaap:DefinedBenefitPlanFairValueOfPlanAssets


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value12381027837926
Percentage of DefinedBenefitPlanFairValueOfPlanAssets100.0100.0100.0100.0

us-gaap:DefinedBenefitPlanFundedStatusOfPlan us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanFundedStatusOfPlan

us-gaap:OtherPensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value-312810000.0-354580000.0-325400000.0-331820000.0-309390000.0
Percentage of DefinedBenefitPlanFundedStatusOfPlan100.0100.0100.0100.0100.0

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value-29919000.0-23273000.0-22615000.0-20714000.0-25752000.0
Percentage of DefinedBenefitPlanFundedStatusOfPlan9.66.66.96.28.3

us-gaap:SupplementalEmployeeRetirementPlanDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value-53631000.0-47397000.0-40603000.0-45727000.0-43311000.0
Percentage of DefinedBenefitPlanFundedStatusOfPlan17.113.412.513.814.0

us-gaap:DefinedBenefitPlanPlanAssetsTargetAllocationPercentage us-gaap:Range, us-gaap:DefinedBenefitPlanByPlanAssetCategories

us-gaap:DefinedBenefitPlanPlanAssetsTargetAllocationPercentage

srt:Maximum, us-gaap:DefinedBenefitPlanEquitySecurities


Defined
Period End2020-12-31
Value75.0
Percentage of DefinedBenefitPlanPlanAssetsTargetAllocationPercentage100.0

srt:Minimum, us-gaap:DefinedBenefitPlanEquitySecurities


Defined
Period End2020-12-31
Value25.0
Percentage of DefinedBenefitPlanPlanAssetsTargetAllocationPercentage33.3

us-gaap:DueFromRelatedPartiesCurrent dei:LegalEntity

us-gaap:DueFromRelatedPartiesCurrent

swx:CenturiGroupInc.


Due
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value1011131517161516191618
Percentage of DueFromRelatedPartiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DueToAffiliateCurrent dei:LegalEntity

us-gaap:DueToAffiliateCurrent

swx:SouthwestGasCorporation


Due
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value267000.090000.0142000.064000.0309000.0174000.0844000.0270000.0580000.01038000.0472000.0380000.0285000.0194000.0
Percentage of DueToAffiliateCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized

us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized


Employee
Period End2020-12-31
Value4500000.0
Percentage of EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized100.0

us-gaap:FinanceLeaseLiability dei:LegalEntity

us-gaap:FinanceLeaseLiability

swx:CenturiGroupInc.


Finance
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value0.692140.6560.7080.495
Percentage of FinanceLeaseLiability100.0100.0100.0100.0100.0

us-gaap:FinanceLeaseLiabilityCurrent dei:LegalEntity

us-gaap:FinanceLeaseLiabilityCurrent

swx:CenturiGroupInc.


Finance
Period End2020-12-312019-12-31
Value0.20213
Percentage of FinanceLeaseLiabilityCurrent100.0100.0

us-gaap:FinanceLeaseLiabilityNoncurrent dei:LegalEntity

us-gaap:FinanceLeaseLiabilityNoncurrent

swx:CenturiGroupInc.


Finance
Period End2020-12-312019-12-31
Value490000.0355000.0
Percentage of FinanceLeaseLiabilityNoncurrent100.0100.0

us-gaap:FinanceLeaseLiabilityPaymentsDue dei:LegalEntity

us-gaap:FinanceLeaseLiabilityPaymentsDue

swx:CenturiGroupInc.


Finance
Period End2020-12-31
Value752000.0
Percentage of FinanceLeaseLiabilityPaymentsDue100.0

us-gaap:FinanceLeaseLiabilityPaymentsDueNextTwelveMonths dei:LegalEntity

us-gaap:FinanceLeaseLiabilityPaymentsDueNextTwelveMonths

swx:CenturiGroupInc.


Finance
Period End2020-12-31
Value235000.0
Percentage of FinanceLeaseLiabilityPaymentsDueNextTwelveMonths100.0

us-gaap:FinanceLeaseLiabilityPaymentsDueYearFour dei:LegalEntity

us-gaap:FinanceLeaseLiabilityPaymentsDueYearFour

swx:CenturiGroupInc.


Finance
Period End2020-12-31
Value1000.0
Percentage of FinanceLeaseLiabilityPaymentsDueYearFour100.0

us-gaap:FinanceLeaseLiabilityPaymentsDueYearThree dei:LegalEntity

us-gaap:FinanceLeaseLiabilityPaymentsDueYearThree

swx:CenturiGroupInc.


Finance
Period End2020-12-31
Value275000.0
Percentage of FinanceLeaseLiabilityPaymentsDueYearThree100.0

us-gaap:FinanceLeaseLiabilityPaymentsDueYearTwo dei:LegalEntity

us-gaap:FinanceLeaseLiabilityPaymentsDueYearTwo

swx:CenturiGroupInc.


Finance
Period End2020-12-31
Value241000.0
Percentage of FinanceLeaseLiabilityPaymentsDueYearTwo100.0

us-gaap:FinanceLeaseLiabilityUndiscountedExcessAmount dei:LegalEntity

us-gaap:FinanceLeaseLiabilityUndiscountedExcessAmount

swx:CenturiGroupInc.


Finance
Period End2020-12-31
Value60000.0
Percentage of FinanceLeaseLiabilityUndiscountedExcessAmount100.0

us-gaap:FinanceLeaseRightOfUseAsset dei:LegalEntity

us-gaap:FinanceLeaseRightOfUseAsset

swx:CenturiGroupInc.


Finance
Period End2020-12-312019-12-31
Value0.75214
Percentage of FinanceLeaseRightOfUseAsset100.0100.0

us-gaap:FinanceLeaseWeightedAverageDiscountRatePercent dei:LegalEntity

us-gaap:FinanceLeaseWeightedAverageDiscountRatePercent

swx:CenturiGroupInc.


Finance
Period End2020-12-312019-12-31
Value5.556.1
Percentage of FinanceLeaseWeightedAverageDiscountRatePercent100.0100.0

us-gaap:FiniteLivedIntangibleAssetsAccumulatedAmortization dei:LegalEntity

us-gaap:FiniteLivedIntangibleAssetsAccumulatedAmortization

swx:CenturiGroupInc.


Finite
Period End2020-12-312019-12-312018-12-31
Value402918
Percentage of FiniteLivedIntangibleAssetsAccumulatedAmortization100.0100.0100.0

us-gaap:FiniteLivedIntangibleAssetsAccumulatedAmortization dei:LegalEntity, us-gaap:FiniteLivedIntangibleAssetsByMajorClass

swx:CenturiGroupInc., us-gaap:CustomerContracts


Finite
Period End2020-12-312019-12-312018-12-31
Value0.270.2520.003
Percentage of FiniteLivedIntangibleAssetsAccumulatedAmortization0.70.90.0

swx:CenturiGroupInc., us-gaap:CustomerRelationships


Finite
Period End2020-12-312019-12-312018-12-31
Value292011
Percentage of FiniteLivedIntangibleAssetsAccumulatedAmortization72.470.765.0

swx:CenturiGroupInc., us-gaap:NoncompeteAgreements


Finite
Period End2020-12-312019-12-312018-12-31
Value1.9311.6021.064
Percentage of FiniteLivedIntangibleAssetsAccumulatedAmortization4.85.55.9

swx:CenturiGroupInc., us-gaap:TrademarksAndTradeNames


Finite
Period End2020-12-312019-12-312018-12-31
Value8.9546.7545.234
Percentage of FiniteLivedIntangibleAssetsAccumulatedAmortization22.223.029.1

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive dei:LegalEntity

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive

swx:CenturiGroupInc.


Finite
Period End2020-12-31
Value88
Percentage of FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive100.0

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths dei:LegalEntity

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths

swx:CenturiGroupInc.


Finite
Period End2020-12-31
Value10
Percentage of FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths100.0

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearFive dei:LegalEntity

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearFive

swx:CenturiGroupInc.


Finite
Period End2020-12-31
Value10
Percentage of FiniteLivedIntangibleAssetsAmortizationExpenseYearFive100.0

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearFour dei:LegalEntity

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearFour

swx:CenturiGroupInc.


Finite
Period End2020-12-31
Value10
Percentage of FiniteLivedIntangibleAssetsAmortizationExpenseYearFour100.0

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearThree dei:LegalEntity

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearThree

swx:CenturiGroupInc.


Finite
Period End2020-12-31
Value10
Percentage of FiniteLivedIntangibleAssetsAmortizationExpenseYearThree100.0

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo dei:LegalEntity

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo

swx:CenturiGroupInc.


Finite
Period End2020-12-31
Value10
Percentage of FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo100.0

us-gaap:FiniteLivedIntangibleAssetsGross dei:LegalEntity

us-gaap:FiniteLivedIntangibleAssetsGross

swx:CenturiGroupInc.


Finite
Period End2020-12-312019-12-312018-12-31
Value180179177
Percentage of FiniteLivedIntangibleAssetsGross100.0100.0100.0

us-gaap:FiniteLivedIntangibleAssetsGross