FIXX


Line plots across dimensions of each concept
Tables

Table of contents



us-gaap:CommonStockValue
us-gaap:StatementEquityComponents
us-gaap:SharesOutstanding

us-gaap:CommonStockSharesIssued

us-gaap:CommonStockSharesAuthorized

us-gaap:PreferredStockSharesAuthorized

us-gaap:CommonStockSharesOutstanding

us-gaap:WeightedAverageNumberOfShareOutstandingBasicAndDiluted

us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecurities

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax
us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

us-gaap:Revenues

us-gaap:OperatingExpenses

us-gaap:ResearchAndDevelopmentExpense

us-gaap:GeneralAndAdministrativeExpense

us-gaap:OperatingIncomeLoss

us-gaap:OtherNonoperatingIncomeExpense

us-gaap:AllocatedShareBasedCompensationExpense
us-gaap:IncomeStatementLocation
us-gaap:PlanName

us-gaap:ProfitLoss

us-gaap:NetIncomeLoss
us-gaap:StatementEquityComponents

us-gaap:ComprehensiveIncomeNetOfTax

us-gaap:Assets

us-gaap:Liabilities

us-gaap:LiabilitiesAndStockholdersEquity

us-gaap:StockholdersEquity
us-gaap:StatementEquityComponents

us-gaap:AssetsCurrent

us-gaap:CashAndCashEquivalentsAtCarryingValue
us-gaap:CounterpartyName, us-gaap:BalanceSheetLocation, us-gaap:TypeOfArrangement
us-gaap:AccountsReceivableNetCurrent

us-gaap:PrepaidExpenseAndOtherAssetsCurrent

us-gaap:PropertyPlantAndEquipmentGross
us-gaap:PropertyPlantAndEquipmentByType

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment

us-gaap:PropertyPlantAndEquipmentNet

us-gaap:OperatingLeaseRightOfUseAsset

us-gaap:LiabilitiesCurrent

us-gaap:AccountsPayableCurrent

us-gaap:OtherAccruedLiabilitiesCurrent

us-gaap:OperatingLeaseLiabilityCurrent

us-gaap:ContractWithCustomerLiabilityCurrent

us-gaap:StockholdersEquity
us-gaap:StatementEquityComponents

us-gaap:CommonStockValue

us-gaap:AdditionalPaidInCapitalCommonStock

us-gaap:RetainedEarningsAccumulatedDeficit

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetIncomeLoss
us-gaap:StatementEquityComponents

us-gaap:ProfitLoss

us-gaap:IncreaseDecreaseInAccountsPayable

us-gaap:ShareBasedCompensation

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

fixx:DeferredOfferingCostsIncludedInAccountsPayableAndAccruedExpenses
us-gaap:Range, us-gaap:SubsidiarySaleOfStock
fixx:ProceedsFromFutureIssuanceStock
us-gaap:SubsidiarySaleOfStock

fixx:ReclassificationOfLiabilityForCommonStockVestedInNoncashTransactions
us-gaap:Range
fixx:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsFairValueOfCommonStock
us-gaap:StatementEquityComponents
fixx:StockIssuedDuringPeriodSharesVestingOfCommonStockFromOptionExercise

fixx:StockIssuedDuringPeriodValueVestingOfCommonStockFromOptionExercise
us-gaap:StatementEquityComponents

us-gaap:AccretionAmortizationOfDiscountsAndPremiumsInvestments

us-gaap:AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition
us-gaap:StatementEquityComponents

us-gaap:CapitalExpendituresIncurredButNotYetPaid

us-gaap:Depreciation

us-gaap:EarningsPerShareBasicAndDiluted

us-gaap:IncreaseDecreaseInAccruedLiabilitiesAndOtherOperatingLiabilities

us-gaap:IncreaseDecreaseInContractWithCustomerLiability

us-gaap:IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets

us-gaap:InvestmentIncomeNonoperating

us-gaap:OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent
us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax

us-gaap:PaymentsOfStockIssuanceCosts

us-gaap:ProceedsFromSaleOfAvailableForSaleSecuritiesDebt

us-gaap:ProceedsFromStockOptionsExercised

us-gaap:ProceedsFromStockPlans
us-gaap:PlanName

us-gaap:PropertyPlantAndEquipmentDisposals

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
us-gaap:PlanName
us-gaap:StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans
us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodSharesStockOptionsExercised
us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodValueEmployeeStockPurchasePlan
us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodValueStockOptionsExercised
us-gaap:StatementEquityComponents

fixx:AccruedExpensesAndOtherLiabilitiesCurrent

fixx:AccruedResearchAndDevelopmentExpensesCurrent

fixx:AccruedUnvestedCommonStockSubjectToRepurchaseCurrent

fixx:UnvestedCommonSharesSubjectToRepurchaseOutstanding

us-gaap:AccruedProfessionalFeesCurrent
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:AssetsFairValueDisclosure
us-gaap:FairValueByMeasurementFrequency

us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
us-gaap:InvestmentType

us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
us-gaap:InvestmentType

us-gaap:AvailableForSaleDebtSecuritiesAmortizedCostBasis
us-gaap:CashAndCashEquivalents
us-gaap:InvestmentType

us-gaap:AvailableForSaleSecuritiesDebtSecurities
us-gaap:CashAndCashEquivalents
us-gaap:InvestmentType

us-gaap:AvailableForSaleSecuritiesDebtSecuritiesCurrent
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, us-gaap:InvestmentType
us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByMeasurementFrequency, us-gaap:InvestmentType
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:CashAndCashEquivalentsFairValueDisclosure
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, us-gaap:InvestmentType
us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByMeasurementFrequency, us-gaap:InvestmentType

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations
us-gaap:CounterpartyName, us-gaap:TypeOfArrangement
us-gaap:ContractWithCustomerLiability

us-gaap:ContractWithCustomerLiabilityNoncurrent

us-gaap:EmployeeRelatedLiabilitiesCurrent

us-gaap:OperatingLeaseLiability

us-gaap:RestrictedCash
us-gaap:CounterpartyName
us-gaap:RevenueRemainingPerformanceObligation
us-gaap:CreditFacility
us-gaap:SecurityDepositLiability
us-gaap:PlanName
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue

Tables

  2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
us-gaap:CommonStockValue █████▆▆▇▇▁0.0040.0040.0040.0040.0040.0030.0030.0037330.0037260.00027
 us-gaap:SharesOutstanding us-gaap:StatementEquityComponents us-gaap:CommonStock█████▇▇▇▇▁45.21065345.20606645.11674243.9560743.86961437.43729737.35852637.31006337.2549022.697352
us-gaap:CommonStockSharesIssued █████▇▇▇▇▁45.21576645.2121945.13840844.02864743.95829537.55700237.50981537.49406137.4746492.928313
us-gaap:CommonStockSharesAuthorized █████████▁200.0200.0200.0200.0200.0200.0200.0200.0200.0170.0
us-gaap:PreferredStockSharesAuthorized ▄▄▄▄▄▄▄▄▄10.010.010.010.010.010.010.010.010.0NA
us-gaap:CommonStockSharesOutstanding █████▇▇▇▇▁45.21065345.20606645.11674243.9560743.86961437.43729737.35852637.31006337.2549022.697352
us-gaap:WeightedAverageNumberOfShareOutstandingBasicAndDiluted █▁45.20793445.151265NA43.90481243.07558737.384507NA37.27340236.8606192.500178
us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount NA5.453939NANANA3.752526NANANA27.084022
 us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecurities fixx:UnvestedCommonStockFromEarlyExerciseOfOptionsNA0.006124NANANA0.119705NANANA0.230961
 us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecurities us-gaap:EmployeeStockOptionNA5.447815NANANA3.632821NANANA2.684405
  2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax ▂▂▂▂▁▁█▃▃▄0.5670.5880.5630.4410.3920.272.6180020.9541490.9264771.129
us-gaap:Revenues ▄▄▄▃▂▁██▇▆0.5670.5880.5630.4410.3920.270.9800020.9541490.9264770.823372
us-gaap:OperatingExpenses ██▅▇▆▅▄▂▂▁36.26437.0826.12231.72928.36525.39321.36727517.23710214.81720611.825627
us-gaap:ResearchAndDevelopmentExpense ▇█▅▇▆▅▄▃▂▁27.47129.3120.34225.69122.82720.53616.28060413.39375910.2898717.997605
us-gaap:GeneralAndAdministrativeExpense █▇▄▄▃▂▃▁▂▁8.7937.775.786.0385.5384.8575.0866713.8433434.5273353.828022
us-gaap:OperatingIncomeLoss ▁▁▄▂▃▄▅▇▇█-35.697-36.492-25.559-31.288-27.973-25.123-20.387273-16.282953-13.890729-11.002255
us-gaap:OtherNonoperatingIncomeExpense ▁▅▆██▆▆▇▄▂0.3571.1611.3921.6611.7031.2711.3858341.487190.9964930.479483
us-gaap:AllocatedShareBasedCompensationExpense █▇▆▅▅▃▂▂▁▁3.4522.8832.4361.9871.9691.2430.955210.7185980.5690720.38012
us-gaap:ProfitLoss ▁▁▄▃▄▄▆▇▇█-35.34-35.331-24.167-29.627-26.27-23.852-19.001439-14.795763-13.200798-10.217
us-gaap:NetIncomeLoss ▁▁▄▃▄▄▆▇▇█-35.34-35.331-24.167-29.627-26.27-23.852-19.001439-14.795763-12.894236-10.522772
 us-gaap:NetIncomeLoss us-gaap:StatementEquityComponents us-gaap:RetainedEarnings▁█-35.34-35.331NA-29.627-26.27-23.852-19.001439-14.148-12.426-10.217
us-gaap:ComprehensiveIncomeNetOfTax ▁▁▄▃▄▄▆▇▇█-35.31-35.533-24.238-29.559-26.09-23.769-19.057869-14.767995-12.856717-10.535629
  2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
  2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
  2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
us-gaap:Assets ▅▆▇▇█▄▅▆▆▁258.238288.788310.567316.759341.156233.026259.094268.396823270.314772129.078151
us-gaap:Liabilities █▇▄▆▆▆█▅▂▁63.53462.24752.0658.93756.41458.76264.37755.63664843.51634140.840872
us-gaap:LiabilitiesAndStockholdersEquity ▅▆▇▇█▄▅▆▆▁258.238288.788310.567316.759341.156233.026259.094268.396823270.314772129.078151
us-gaap:StockholdersEquity ▆▇▇▇█▆▆▆▇▁194.704226.541258.507257.822284.742174.264194.717212.760175226.798431-49.524881
  2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
us-gaap:AssetsCurrent ▅▆▇▇█▄▅▆▇▁209.807238.333266.577274.079298.769190.502221.685245.866343261.582353120.404902
us-gaap:CashAndCashEquivalentsAtCarryingValue █▇▂▃▅▁▁▁▄▂167.636143.37253.77477.559115.56640.83938.2236.03839194.96053546.213413
 us-gaap:AccountsReceivableNetCurrent us-gaap:CounterpartyName,us-gaap:BalanceSheetLocation,us-gaap:TypeOfArrangement fixx:NovartisInstitutesOfBioMedicalResearchInc,fixx:ReimbursableResearchAndDevelopmentCosts,us-gaap:CollaborativeArrangement▃▃▃▂▂▁█0.40.40.40.30.30.20.8NANANA
us-gaap:PrepaidExpenseAndOtherAssetsCurrent ▂▂▃▃▂▁▆█▅▂3.1643.4044.1894.4072.9732.5356.9488.3223246.0742683.672428
  2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
us-gaap:PropertyPlantAndEquipmentGross ███▇▆▆▅▁53.0852.88351.12648.11346.12944.35837.74522.363985NANA
us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment █▇▅▄▃▂▁▁12.30910.3178.416.7075.0163.3742.1081.623467NANA
us-gaap:PropertyPlantAndEquipmentNet ██████▇▄▂▁40.77142.56642.71641.40641.11340.98435.63720.7405186.9424573.828104
us-gaap:OperatingLeaseRightOfUseAsset ▁█6.3866.615NANANANANANANANA
  2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
us-gaap:LiabilitiesCurrent ▅▅▂▅▄▅█▅▂▁19.56417.45212.37418.68215.49117.64725.43318.57397510.8755599.442066
us-gaap:AccountsPayableCurrent ▃▄▁▄▄▆█▆▂▂7.1037.3982.6088.7988.33411.79415.73211.1208835.0174263.776474
us-gaap:OtherAccruedLiabilitiesCurrent ▃▂▃█▄▁▄0.2530.220.2560.4420.2880.1790.304NANANA
us-gaap:OperatingLeaseLiabilityCurrent █▁2.4132.331NANANANANANANANA
us-gaap:ContractWithCustomerLiabilityCurrent ▄▄▅▄▁█▄0.7740.7740.8090.7740.690.9050.77NANANA
  2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
  2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
us-gaap:StockholdersEquity ▆▇▇▇█▆▆▆▇▁194.704226.541258.507257.822284.742174.264194.717212.760175226.798431-49.524881
us-gaap:CommonStockValue █████▆▆▇▇▁0.0040.0040.0040.0040.0040.0030.0030.0037330.0037260.00027
us-gaap:AdditionalPaidInCapitalCommonStock ████▇▅▅▅▅▁465.034461.561457.994433.071430.432293.865292.187291.171747290.4420151.264652
us-gaap:RetainedEarningsAccumulatedDeficit ▁▂▃▄▅▆▇▇██-270.345-235.005-199.674-175.507-145.88-119.61-97.396-78.394427-63.598664-50.703638
us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax ▃▂▇█▇▃▁▂▂▁0.011-0.0190.1830.2540.1860.006-0.077-0.020878-0.048646-0.086165
  2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
us-gaap:NetCashProvidedByUsedInOperatingActivities ▁▂▂▂▃▅█▆▇▇-27.987-25.846-26.333-25.484-21.67-17.871-8.078951-13.691725-9.747324-11.044
us-gaap:NetCashProvidedByUsedInInvestingActivities ▆█▃▄▃▅▄▃▁▄52.01114.997-20.027-13.137-38.30219.66710.219411-45.254822-93.3915896.64
us-gaap:NetCashProvidedByUsedInFinancingActivities ▁▁▂▁▇▁▁▁█▁0.2410.44722.5750.614134.6990.3250.0410810.024403151.886516-0.958
us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect ▅█▃▂▇▄▄▁▆▄24.26489.598-23.785-38.00774.7272.1212.164-58.92248.765-5.362
  2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
us-gaap:NetCashProvidedByUsedInOperatingActivities ▁▂▂▂▃▅█▆▇▇-27.987-25.846-26.333-25.484-21.67-17.871-8.078951-13.691725-9.747324-11.044
us-gaap:NetIncomeLoss ▁▁▄▃▄▄▆▇▇█-35.34-35.331-24.167-29.627-26.27-23.852-19.001439-14.795763-12.894236-10.522772
 us-gaap:NetIncomeLoss us-gaap:StatementEquityComponents us-gaap:RetainedEarnings▁█-35.34-35.331NA-29.627-26.27-23.852-19.001439-14.148-12.426-10.217
us-gaap:ProfitLoss ▁▁▄▃▄▄▆▇▇█-35.34-35.331-24.167-29.627-26.27-23.852-19.001439-14.795763-13.200798-10.217
us-gaap:IncreaseDecreaseInAccountsPayable ▅█▁▅▅▅█▃▆▅0.0794.841-5.9630.9350.661-0.0854.954193-3.1378922.055810.510889
us-gaap:ShareBasedCompensation █▇▆▅▅▃▂▂▁▁3.4532.8832.4361.9861.971.2430.955210.7185980.5690720.38012
  2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
us-gaap:NetCashProvidedByUsedInInvestingActivities ▆█▃▄▃▅▄▃▁▄52.01114.997-20.027-13.137-38.30219.66710.219411-45.254822-93.3915896.64
us-gaap:PaymentsToAcquirePropertyPlantAndEquipment ▁▂▂▂▃▆█▃▂▁0.5882.0333.7251.7235.91910.46615.9301274.8247373.1490271.035109
  2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
us-gaap:NetCashProvidedByUsedInFinancingActivities ▁▁▂▁▇▁▁▁█▁0.2410.44722.5750.614134.6990.3250.0410810.024403151.886516-0.958
  2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31

None

us-gaap:CommonStockValue

us-gaap:CommonStockValue


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value4000.04000.04000.04000.04000.03000.03000.03733.03726.0270.0264.0
Percentage of CommonStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.0

None

us-gaap:SharesOutstanding us-gaap:StatementEquityComponents

us-gaap:SharesOutstanding

us-gaap:CommonStock


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-31
Value4545454343373737372.6973522.6370112.121156
Percentage of SharesOutstanding100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

None

us-gaap:CommonStockSharesIssued

us-gaap:CommonStockSharesIssued


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value4545454443373737372.9283132.902109
Percentage of CommonStockSharesIssued100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

None

us-gaap:CommonStockSharesAuthorized

us-gaap:CommonStockSharesAuthorized


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value200200200200200200200200200170170
Percentage of CommonStockSharesAuthorized100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

None

us-gaap:PreferredStockSharesAuthorized

us-gaap:PreferredStockSharesAuthorized


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value10000000.010000000.010000000.010000000.010000000.010000000.010000000.010000000.010000000.00
Percentage of PreferredStockSharesAuthorized100.0100.0100.0100.0100.0100.0100.0100.0100.00.0

None

us-gaap:CommonStockSharesOutstanding

us-gaap:CommonStockSharesOutstanding


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value4545454343373737372.6973522.637011
Percentage of CommonStockSharesOutstanding100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

None

us-gaap:WeightedAverageNumberOfShareOutstandingBasicAndDiluted

us-gaap:WeightedAverageNumberOfShareOutstandingBasicAndDiluted


None
Period End2020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-31
Value454543433737362.5001782.3513982.2961181.992014
Percentage of WeightedAverageNumberOfShareOutstandingBasicAndDiluted100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

None

us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount

us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount


None
Period End2020-03-312019-03-312018-03-312017-03-31
Value5.4539393.7525262713
Percentage of AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount100.0100.0100.0100.0

us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecurities

fixx:UnvestedCommonStockFromEarlyExerciseOfOptions


None
Period End2020-03-312019-03-312018-03-312017-03-31
Value0.0061240.1197050.2309610.618742
Percentage of AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount0.13.20.94.7

us-gaap:EmployeeStockOption


None
Period End2020-03-312019-03-312018-03-312017-03-31
Value5.4478153.6328212.6844050.734218
Percentage of AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount99.996.89.95.6

None

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value567000.0588000.0563000.0441000.0392000.0270000.02618000.0954150.0926480.01129000.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues100.0100.00.0100.0100.0100.00.0100.0100.0137.1

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

fixx:NovartisInstitutesOfBioMedicalResearchInc, us-gaap:CollaborativeArrangement


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value600000.0600000.0600000.0400000.0400000.0300000.02600000.01600000.01400000.01100000.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax105.8102.0106.690.7102.0111.199.3167.7151.197.4
Percentage of Revenues105.8102.00.090.7102.0111.10.0167.7151.1133.6
Percentage of Revenues fixx:NovartisInstitutesOfBioMedicalResearchInc us-gaap:CollaborativeArrangement0.00.00.00.00.00.00.00.00.0133.7

None

us-gaap:Revenues

us-gaap:Revenues


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value567000.0588000.0563000.0441000.0392000.0270000.0980000.0954150.0926480.0823370.0
Percentage of Revenues100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

None

us-gaap:OperatingExpenses

us-gaap:OperatingExpenses


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value36372631282521171411126.664776.038524.691518
Percentage of OperatingExpenses100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues6395.86306.14639.87194.87236.09404.82180.31806.51599.31436.20.00.00.00.0

None

us-gaap:ResearchAndDevelopmentExpense

us-gaap:ResearchAndDevelopmentExpense


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value2729202522201613107.9976059.5761284.9466114.0562892.799136
Percentage of ResearchAndDevelopmentExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues4845.04984.73613.15825.65823.27605.91661.31403.71110.6971.30.00.00.00.0

None

us-gaap:GeneralAndAdministrativeExpense

us-gaap:GeneralAndAdministrativeExpense


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value8.7937.775.786.0385.5384.8575.0866713.8433434.5273353.8280222.6860631.7181591.9822311.892382
Percentage of GeneralAndAdministrativeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues1550.81321.41026.61369.21412.81798.9519.0402.8488.7464.90.00.00.00.0

None

us-gaap:OperatingIncomeLoss

us-gaap:OperatingIncomeLoss


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-35697000.0-36492000.0-25559000.0-31288000.0-27973000.0-25123000.0-20387000.0-16283000.0-13891000.0-11002000.0-12262000.0-6664800.0-6038500.0-4691500.0
Percentage of OperatingIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues-6295.8-6206.1-4539.8-7094.8-7136.0-9304.8-2080.3-1706.5-1499.3-1336.20.00.00.00.0

None

us-gaap:OtherNonoperatingIncomeExpense

us-gaap:OtherNonoperatingIncomeExpense


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value357000.01161000.01392000.01661000.01703000.01271000.01385800.01487200.0996490.0479480.0356310.0137200.035766.0-863280.0
Percentage of OtherNonoperatingIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues63.0197.4247.2376.6434.4470.7141.4155.9107.658.20.00.00.00.0

None

us-gaap:AllocatedShareBasedCompensationExpense

us-gaap:AllocatedShareBasedCompensationExpense


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value3452000.02883000.02436000.01987000.01969000.01243000.0955210.0718600.0569070.0380120.0139860.057884.030578.027680.0
Percentage of AllocatedShareBasedCompensationExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues608.8490.3432.7450.6502.3460.497.575.361.446.20.00.00.00.0

us-gaap:AllocatedShareBasedCompensationExpense us-gaap:IncomeStatementLocation

us-gaap:GeneralAndAdministrativeExpense


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value1698000.01570000.01058000.0863000.0865000.0685000.0464020.0393130.0401770.0247080.076898.027967.019316.016819.0
Percentage of AllocatedShareBasedCompensationExpense49.254.543.443.443.955.148.654.770.665.055.048.363.260.8
Percentage of Revenues299.5267.0187.9195.7220.7253.747.341.243.430.00.00.00.00.0
Percentage of Revenues us-gaap:GeneralAndAdministrativeExpense0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:ResearchAndDevelopmentExpense


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value1754000.01313000.01378000.01124000.01104000.0558000.0491190.0325470.0167310.0133040.062960.029917.011262.010861.0
Percentage of AllocatedShareBasedCompensationExpense50.845.556.656.656.144.951.445.329.435.045.051.736.839.2
Percentage of Revenues309.3223.3244.8254.9281.6206.750.134.118.116.20.00.00.00.0
Percentage of Revenues us-gaap:ResearchAndDevelopmentExpense0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AllocatedShareBasedCompensationExpense us-gaap:PlanName

fixx:TwentyEighteenEmployeeStockPurchasePlan


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value100000.00100000.0100000.0100000.00
Percentage of AllocatedShareBasedCompensationExpense2.90.04.15.05.10.0
Percentage of Revenues17.60.017.822.725.50.0
Percentage of Revenues fixx:TwentyEighteenEmployeeStockPurchasePlan0.00.00.00.00.00.0

None

us-gaap:ProfitLoss

us-gaap:ProfitLoss


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-35340000.0-35331000.0-24167000.0-29627000.0-26270000.0-23852000.0-19001000.0-14796000.0-13201000.0-10217000.0-11906000.0-6527600.0
Percentage of ProfitLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues-6232.8-6008.7-4292.5-6718.1-6701.5-8834.1-1938.9-1550.7-1424.8-1240.90.00.0

None

us-gaap:NetIncomeLoss

us-gaap:NetIncomeLoss


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-35340000.0-35331000.0-24167000.0-29627000.0-26270000.0-23852000.0-19001000.0-14796000.0-12894000.0-10523000.0-11906000.0-6527600.0-6002800.0-5554800.0
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues-6232.8-6008.7-4292.5-6718.1-6701.5-8834.1-1938.9-1550.7-1391.7-1278.00.00.00.00.0

us-gaap:NetIncomeLoss us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings


None
Period End2020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-35340000.0-35331000.0-29627000.0-26270000.0-23852000.0-19001000.0-14148000.0-12426000.0-10217000.0
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.095.696.497.1
Percentage of Revenues-6232.8-6008.7-6718.1-6701.5-8834.1-1938.9-1482.8-1341.2-1240.9
Percentage of Revenues us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.0

None

us-gaap:ComprehensiveIncomeNetOfTax

us-gaap:ComprehensiveIncomeNetOfTax


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-35310000.0-35533000.0-24238000.0-29559000.0-26090000.0-23769000.0-19058000.0-14768000.0-12857000.0-10536000.0-11979000.0-6527600.0-6002800.0-5554800.0
Percentage of ComprehensiveIncomeNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues-6227.5-6043.0-4305.2-6702.7-6655.6-8803.3-1944.7-1547.8-1387.7-1279.60.00.00.00.0

None

us-gaap:Assets

us-gaap:Assets


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value258288310316341233259268270129137
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

None

us-gaap:Liabilities

us-gaap:Liabilities


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value6362525856586455434039
Percentage of Liabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets24.621.616.818.616.525.224.820.716.131.628.5

None

us-gaap:LiabilitiesAndStockholdersEquity

us-gaap:LiabilitiesAndStockholdersEquity


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value258288310316341233259268270129137
Percentage of LiabilitiesAndStockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

None

us-gaap:StockholdersEquity

us-gaap:StockholdersEquity


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-31
Value194226258257284174194212226-49.524881-39.454051-9.892
Percentage of StockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets75.478.483.281.483.574.875.279.383.9-38.4-28.70.0

us-gaap:StockholdersEquity us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value0.011-0.0190.1830.2540.1860.006-0.077-0.020878-0.048646-0.086-0.073308
Percentage of StockholdersEquity0.0-0.00.10.10.10.0-0.0-0.0-0.00.20.2
Percentage of Assets0.0-0.00.10.10.10.0-0.0-0.0-0.0-0.1-0.1
Percentage of Assets us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AdditionalPaidInCapital


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-31
Value4654614574334302932922912901.2650.7998590.298
Percentage of StockholdersEquity238.8203.7177.2168.0151.2168.6150.1136.9128.1-2.6-2.0-3.0
Percentage of Assets180.1159.8147.5136.7126.2126.1112.8108.5107.41.00.60.0
Percentage of Assets us-gaap:AdditionalPaidInCapital0.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:CommonStock


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value0.0040.0040.0040.0040.0040.0030.0030.0037330.0037260.000264
Percentage of StockholdersEquity0.00.00.00.00.00.00.00.00.0-0.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.0
Percentage of Assets us-gaap:CommonStock0.00.00.00.00.00.00.00.00.00.0

us-gaap:RetainedEarnings


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-31
Value-270.345-235.005-199.674-175.507-145.88-119.61-97.396-78.394427-63.598664-50.398-40.180866-10.19
Percentage of StockholdersEquity-138.8-103.7-77.2-68.1-51.2-68.6-50.0-36.8-28.0101.8101.8103.0
Percentage of Assets-104.7-81.4-64.3-55.4-42.8-51.3-37.6-29.2-23.5-39.0-29.20.0
Percentage of Assets us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.0

None

us-gaap:AssetsCurrent

us-gaap:AssetsCurrent


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value209238266274298190221245261120131
Percentage of AssetsCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets81.282.585.886.587.681.885.691.696.893.395.7

None

us-gaap:CashAndCashEquivalentsAtCarryingValue

us-gaap:CashAndCashEquivalentsAtCarryingValue


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value167143537711540383694465197202611
Percentage of CashAndCashEquivalentsAtCarryingValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets64.949.617.324.533.917.514.813.435.135.837.50.00.00.00.0

None

us-gaap:AccountsReceivableNetCurrent us-gaap:CounterpartyName, us-gaap:BalanceSheetLocation, us-gaap:TypeOfArrangement

us-gaap:AccountsReceivableNetCurrent

fixx:NovartisInstitutesOfBioMedicalResearchInc, fixx:ReimbursableResearchAndDevelopmentCosts, us-gaap:CollaborativeArrangement


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value400000.0400000.0400000.0300000.0300000.0200000.0800000.0
Percentage of AccountsReceivableNetCurrent100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.20.10.10.10.10.10.3
Percentage of Assets fixx:NovartisInstitutesOfBioMedicalResearchInc fixx:ReimbursableResearchAndDevelopmentCosts us-gaap:CollaborativeArrangement0.00.00.00.00.00.00.0

None

us-gaap:PrepaidExpenseAndOtherAssetsCurrent

us-gaap:PrepaidExpenseAndOtherAssetsCurrent


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value3164000.03404000.04189000.04407000.02973000.02535000.06948000.08322300.06074300.03672400.01944800.0
Percentage of PrepaidExpenseAndOtherAssetsCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.21.21.31.40.91.12.73.12.22.81.4

None

us-gaap:PropertyPlantAndEquipmentGross

us-gaap:PropertyPlantAndEquipmentGross


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value53525148464437224.051847
Percentage of PropertyPlantAndEquipmentGross100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets20.618.316.515.213.519.014.68.32.9

us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType

fixx:AssetNotYetInService


None
Period End2020-06-302020-03-312019-12-312019-09-302019-03-312018-12-312018-09-30
Value0.8951.1682.5130.8952.3112.6021.525008
Percentage of PropertyPlantAndEquipmentGross1.72.24.91.95.26.96.8
Percentage of Assets0.30.40.80.31.01.00.6
Percentage of Assets fixx:AssetNotYetInService0.00.00.00.00.00.00.0

us-gaap:ComputerEquipment


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value1.5961.2150.640.6110.5210.4870.2480.2728420.252436
Percentage of PropertyPlantAndEquipmentGross3.02.31.31.31.11.10.71.26.2
Percentage of Assets0.60.40.20.20.20.20.10.10.2
Percentage of Assets us-gaap:ComputerEquipment0.00.00.00.00.00.00.00.00.0

us-gaap:Equipment


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value7.4317.4794.9114.7564.5231.113
Percentage of PropertyPlantAndEquipmentGross14.014.19.69.99.82.5
Percentage of Assets2.92.61.61.51.30.5
Percentage of Assets us-gaap:Equipment0.00.00.00.00.00.0

us-gaap:FurnitureAndFixtures


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value1.3631.3631.3631.3861.3861.2361.0660.0513790.051379
Percentage of PropertyPlantAndEquipmentGross2.62.62.72.93.02.82.80.21.3
Percentage of Assets0.50.50.40.40.40.50.40.00.0
Percentage of Assets us-gaap:FurnitureAndFixtures0.00.00.00.00.00.00.00.00.0

us-gaap:LeaseholdImprovements


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value29293030292924150.03412
Percentage of PropertyPlantAndEquipmentGross56.456.760.463.164.265.765.067.60.8
Percentage of Assets11.610.49.99.68.712.59.55.60.0
Percentage of Assets us-gaap:LeaseholdImprovements0.00.00.00.00.00.00.00.00.0

us-gaap:OfficeEquipment


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value1111101010109.3095.3876273.713912
Percentage of PropertyPlantAndEquipmentGross22.322.121.221.021.922.724.724.191.7
Percentage of Assets4.64.13.53.23.04.33.62.02.7
Percentage of Assets us-gaap:OfficeEquipment0.00.00.00.00.00.00.00.00.0

None

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value12108.416.7075.0163.3742.1081.6234670.897642
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets4.83.62.72.11.51.40.80.60.7

None

us-gaap:PropertyPlantAndEquipmentNet

us-gaap:PropertyPlantAndEquipmentNet


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value40424241414035206.9424573.8281043.154205
Percentage of PropertyPlantAndEquipmentNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets15.814.713.813.112.117.613.87.72.63.02.3

None

us-gaap:OperatingLeaseRightOfUseAsset

us-gaap:OperatingLeaseRightOfUseAsset


None
Period End2020-06-302020-03-312020-01-01
Value6386000.06615000.06835000.0
Percentage of OperatingLeaseRightOfUseAsset100.0100.0100.0
Percentage of Assets2.52.30.0

None

us-gaap:LiabilitiesCurrent

us-gaap:LiabilitiesCurrent


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value1917121815172518109.4420668.861746
Percentage of LiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets7.66.04.05.94.57.69.86.94.07.36.4

None

us-gaap:AccountsPayableCurrent

us-gaap:AccountsPayableCurrent


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value7.1037.3982.6088.7988.3341115115.0174263.7764742.538057
Percentage of AccountsPayableCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets2.82.60.82.82.45.16.14.11.92.91.8

None

us-gaap:OtherAccruedLiabilitiesCurrent

us-gaap:OtherAccruedLiabilitiesCurrent


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value253000.0220000.0256000.0442000.0288000.0179000.0304000.0
Percentage of OtherAccruedLiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.10.10.10.10.10.10.1

None

us-gaap:OperatingLeaseLiabilityCurrent

us-gaap:OperatingLeaseLiabilityCurrent


None
Period End2020-06-302020-03-312020-01-01
Value2.4132.33115
Percentage of OperatingLeaseLiabilityCurrent100.0100.0100.0
Percentage of Assets0.90.80.0

None

us-gaap:ContractWithCustomerLiabilityCurrent

us-gaap:ContractWithCustomerLiabilityCurrent


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value774000.0774000.0809000.0774000.0690000.0905000.0770000.0
Percentage of ContractWithCustomerLiabilityCurrent100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.30.30.30.20.20.40.3

None

us-gaap:StockholdersEquity

us-gaap:StockholdersEquity


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-31
Value194226258257284174194212226-49.524881-39.454051-9.892
Percentage of StockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets75.478.483.281.483.574.875.279.383.9-38.4-28.70.0

us-gaap:StockholdersEquity us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value0.011-0.0190.1830.2540.1860.006-0.077-0.020878-0.048646-0.086-0.073308
Percentage of StockholdersEquity0.0-0.00.10.10.10.0-0.0-0.0-0.00.20.2
Percentage of Assets0.0-0.00.10.10.10.0-0.0-0.0-0.0-0.1-0.1
Percentage of Assets us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AdditionalPaidInCapital


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-31
Value4654614574334302932922912901.2650.7998590.298
Percentage of StockholdersEquity238.8203.7177.2168.0151.2168.6150.1136.9128.1-2.6-2.0-3.0
Percentage of Assets180.1159.8147.5136.7126.2126.1112.8108.5107.41.00.60.0
Percentage of Assets us-gaap:AdditionalPaidInCapital0.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:CommonStock


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value0.0040.0040.0040.0040.0040.0030.0030.0037330.0037260.000264
Percentage of StockholdersEquity0.00.00.00.00.00.00.00.00.0-0.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.0
Percentage of Assets us-gaap:CommonStock0.00.00.00.00.00.00.00.00.00.0

us-gaap:RetainedEarnings


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-31
Value-270.345-235.005-199.674-175.507-145.88-119.61-97.396-78.394427-63.598664-50.398-40.180866-10.19
Percentage of StockholdersEquity-138.8-103.7-77.2-68.1-51.2-68.6-50.0-36.8-28.0101.8101.8103.0
Percentage of Assets-104.7-81.4-64.3-55.4-42.8-51.3-37.6-29.2-23.5-39.0-29.20.0
Percentage of Assets us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.0

None

us-gaap:CommonStockValue

us-gaap:CommonStockValue


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value4000.04000.04000.04000.04000.03000.03000.03733.03726.0270.0264.0
Percentage of CommonStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.0

None

us-gaap:AdditionalPaidInCapitalCommonStock

us-gaap:AdditionalPaidInCapitalCommonStock


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value4654614574334302932922912901.2646520.799859
Percentage of AdditionalPaidInCapitalCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets180.1159.8147.5136.7126.2126.1112.8108.5107.41.00.6

None

us-gaap:RetainedEarningsAccumulatedDeficit

us-gaap:RetainedEarningsAccumulatedDeficit


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value-270340000.0-235000000.0-199670000.0-175510000.0-145880000.0-119610000.0-97396000.0-78394000.0-63599000.0-50704000.0-40181000.0
Percentage of RetainedEarningsAccumulatedDeficit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets-104.7-81.4-64.3-55.4-42.8-51.3-37.6-29.2-23.5-39.3-29.2

None

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value11000.0-19000.0183000.0254000.0186000.06000.0-77000.0-20878.0-48646.0-86165.0-73308.0
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.0-0.00.10.10.10.0-0.0-0.0-0.0-0.1-0.1

None

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInOperatingActivities


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-27987000.0-25846000.0-26333000.0-25484000.0-21670000.0-17871000.0-8079000.0-13692000.0-9747300.0-11044000.022048000.0-5448900.0
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues-4936.0-4395.6-4677.3-5778.7-5528.1-6618.9-824.4-1435.0-1052.1-1341.30.00.0

None

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value52114-20.027-13.137-38.3021910-45.254822-93.3915896.64-79.904735-0.299538
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues9172.819557.3-3557.2-2978.9-9770.97284.11042.8-4743.0-10080.3806.40.00.0

None

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value0.2410.447220.6141340.3250.0410810.024403151-0.9581183
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues42.576.04009.8139.234362.0120.44.22.616394.0-116.40.00.0

None

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value2489-23.785-38.007742.1212.164-58.92248-5.362
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues4279.415237.8-4224.7-8618.419063.0785.6220.8-6175.35263.5-651.2

None

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInOperatingActivities


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-27.987-25.846-26.333-25.484-21.67-17.871-8.078951-13.691725-9.747324-11.04422-5.448875
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues-4936.0-4395.6-4677.3-5778.7-5528.1-6618.9-824.4-1435.0-1052.1-1341.30.00.0

None

us-gaap:NetIncomeLoss

us-gaap:NetIncomeLoss


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-35340000.0-35331000.0-24167000.0-29627000.0-26270000.0-23852000.0-19001000.0-14796000.0-12894000.0-10523000.0-11906000.0-6527600.0-6002800.0-5554800.0
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues-6232.8-6008.7-4292.5-6718.1-6701.5-8834.1-1938.9-1550.7-1391.7-1278.00.00.00.00.0

us-gaap:NetIncomeLoss us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings


None
Period End2020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-35340000.0-35331000.0-29627000.0-26270000.0-23852000.0-19001000.0-14148000.0-12426000.0-10217000.0
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.095.696.497.1
Percentage of Revenues-6232.8-6008.7-6718.1-6701.5-8834.1-1938.9-1482.8-1341.2-1240.9
Percentage of Revenues us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.0

None

us-gaap:ProfitLoss

us-gaap:ProfitLoss


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value-35340000.0-35331000.0-24167000.0-29627000.0-26270000.0-23852000.0-19001000.0-14796000.0-13201000.0-10217000.0-11906000.0-6527600.0
Percentage of ProfitLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues-6232.8-6008.7-4292.5-6718.1-6701.5-8834.1-1938.9-1550.7-1424.8-1240.90.00.0

None

us-gaap:IncreaseDecreaseInAccountsPayable

us-gaap:IncreaseDecreaseInAccountsPayable


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value79000.04841000.0-5963000.0935000.0661000.0-85000.04954200.0-3137900.02055800.0510890.01188600.0382770.0-201820.0350400.0
Percentage of IncreaseDecreaseInAccountsPayable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

None

us-gaap:ShareBasedCompensation

us-gaap:ShareBasedCompensation


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value3453000.02883000.02436000.01986000.01970000.01243000.0955210.0718600.0569070.0380120.0160860.057884.030578.027680.0
Percentage of ShareBasedCompensation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

None

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value52114-20.027-13.137-38.3021910-45.254822-93.3915896.64-79.904735-0.299538
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues9172.819557.3-3557.2-2978.9-9770.97284.11042.8-4743.0-10080.3806.40.00.0

None

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value0.5882.0333.7251.7235.91910154.8247373.1490271.0351090.3367350.2995380.4732940.848433
Percentage of PaymentsToAcquirePropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

None

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value0.2410.447220.6141340.3250.0410810.024403151-0.9581183
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Revenues42.576.04009.8139.234362.0120.44.22.616394.0-116.40.00.0

None

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value5695900.05447800.04843000.03876400.03896800.03632800.03203100.02696900.02641800.02684400.01971700.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

None

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value15.4915.6314.7813.4513.3112.4410.477.797.377.033.61
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

None

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value16814455781164239379647
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

fixx:DeferredOfferingCostsIncludedInAccountsPayableAndAccruedExpenses

fixx:DeferredOfferingCostsIncludedInAccountsPayableAndAccruedExpenses


None
Period End2020-03-312019-03-312018-03-31
Value77000.0174000.02046000.0
Percentage of DeferredOfferingCostsIncludedInAccountsPayableAndAccruedExpenses100.0100.0100.0

fixx:ProceedsFromFutureIssuanceStock us-gaap:Range, us-gaap:SubsidiarySaleOfStock

fixx:ProceedsFromFutureIssuanceStock

srt:Maximum, fixx:AtTheMarketSalesAgreement


None
Period End2020-03-122019-04-01
Value150100
Percentage of ProceedsFromFutureIssuanceStock100.0100.0

fixx:ProceedsFromFutureIssuanceStock us-gaap:SubsidiarySaleOfStock

fixx:AtTheMarketSalesAgreement


None
Period End2020-06-302020-03-31
Value0.0150
Percentage of ProceedsFromFutureIssuanceStock0.00.0

fixx:ReclassificationOfLiabilityForCommonStockVestedInNoncashTransactions

fixx:ReclassificationOfLiabilityForCommonStockVestedInNoncashTransactions


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value4000.012000.013000.011000.018000.018000.018014.051236.0-9666.015416.0204400.00020605.0
Percentage of ReclassificationOfLiabilityForCommonStockVestedInNoncashTransactions100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0100.0

fixx:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsFairValueOfCommonStock us-gaap:Range

fixx:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsFairValueOfCommonStock

srt:Maximum


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value18.0421.75021.4530.3428.133.320.414.9816.03.74
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsFairValueOfCommonStock100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0

srt:Minimum


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value12.6617.0-3.1915.9219.5121.43015.9606.63
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsFairValueOfCommonStock70.278.20.074.264.376.20.078.20.041.4

fixx:StockIssuedDuringPeriodSharesVestingOfCommonStockFromOptionExercise us-gaap:StatementEquityComponents

fixx:StockIssuedDuringPeriodSharesVestingOfCommonStockFromOptionExercise

us-gaap:CommonStock


None
Period End2020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value1011.015542.016104.031024.031584.035749.027364.034137.0
Percentage of StockIssuedDuringPeriodSharesVestingOfCommonStockFromOptionExercise100.0100.0100.0100.0100.0100.0100.0100.0

fixx:StockIssuedDuringPeriodValueVestingOfCommonStockFromOptionExercise

fixx:StockIssuedDuringPeriodValueVestingOfCommonStockFromOptionExercise


None
Period End2020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value4000.012000.011000.018000.018000.018014.051000.0-10000.016000.0
Percentage of StockIssuedDuringPeriodValueVestingOfCommonStockFromOptionExercise100.0100.0100.0100.0100.0100.0100.0100.0100.0

fixx:StockIssuedDuringPeriodValueVestingOfCommonStockFromOptionExercise us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital


None
Period End2020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value4000.012000.011000.018000.018000.018025.051000.0-10000.016000.0
Percentage of StockIssuedDuringPeriodValueVestingOfCommonStockFromOptionExercise100.0100.0100.0100.0100.0100.1100.0100.0100.0

us-gaap:AccretionAmortizationOfDiscountsAndPremiumsInvestments

us-gaap:AccretionAmortizationOfDiscountsAndPremiumsInvestments


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value18000.0175000.0270000.0401000.0539000.0661000.01200000.0500000.0-234000.0123000.0
Percentage of AccretionAmortizationOfDiscountsAndPremiumsInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition

us-gaap:AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition


None
Period End2020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value3453000.02883000.01986000.01970000.01243000.0719000.0569000.0380000.0
Percentage of AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital


None
Period End2020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value3453000.02883000.01986000.01970000.01243000.0719000.0569000.0380000.0
Percentage of AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CapitalExpendituresIncurredButNotYetPaid

us-gaap:CapitalExpendituresIncurredButNotYetPaid


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-375000.0405000.0-227000.0-444000.0-4148000.05274000.0-343860.09241400.0202530.026980.029905.0-9640.0-67999.0214730.0
Percentage of CapitalExpendituresIncurredButNotYetPaid100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Depreciation

us-gaap:Depreciation


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value2000000.01907000.01719000.01700000.01600000.01266000.0563180.0300000.0200000.0220600.0200610.0200000.0163510.0130160.0
Percentage of Depreciation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EarningsPerShareBasicAndDiluted

us-gaap:EarningsPerShareBasicAndDiluted


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-0.78-0.78-0.55-0.67-0.61-0.64-0.52-0.4-0.35-4.21-4.67-2.78-2.61-2.79
Percentage of EarningsPerShareBasicAndDiluted100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInAccruedLiabilitiesAndOtherOperatingLiabilities

us-gaap:IncreaseDecreaseInAccruedLiabilitiesAndOtherOperatingLiabilities


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value2423000.0-535000.0194000.01819000.01706000.0-1404000.01210800.01476100.01119100.0-763950.0210050.0244530.0478530.0-69114.0
Percentage of IncreaseDecreaseInAccruedLiabilitiesAndOtherOperatingLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInContractWithCustomerLiability

us-gaap:IncreaseDecreaseInContractWithCustomerLiability


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-194000.0-203000.0-190000.0-146000.0-141000.0-92000.0-406000.0-546000.0-475000.0-463000.0
Percentage of IncreaseDecreaseInContractWithCustomerLiability100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets

us-gaap:IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value62000.0-1087000.0-218000.01434000.0438000.0-4413000.0-1374600.02248100.02401800.01727700.01195700.0-223740.0100080.0390920.0
Percentage of IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InvestmentIncomeNonoperating

us-gaap:InvestmentIncomeNonoperating


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value357000.01161000.01392000.01661000.01703000.01271000.01385800.01487200.0996490.0479480.0356310.0137200.035766.012725.0
Percentage of InvestmentIncomeNonoperating100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent

us-gaap:OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value30000.0-202000.0-71000.068000.0180000.083000.0-56430.027768.037519.0-13000.0
Percentage of OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome


None
Period End2020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value30000.0-202000.068000.0180000.083000.0-56430.028000.038000.0-13000.0
Percentage of OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent100.0100.0100.0100.0100.0100.0100.8101.3100.0

us-gaap:OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax

us-gaap:OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value30000.0-202000.0-71000.068000.0180000.083000.0-56430.027768.037519.0-13000.0
Percentage of OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsOfStockIssuanceCosts

us-gaap:PaymentsOfStockIssuanceCosts


None
Period End2020-03-312019-03-312018-03-31
Value225000.092000.01027000.0
Percentage of PaymentsOfStockIssuanceCosts100.0100.0100.0

us-gaap:ProceedsFromSaleOfAvailableForSaleSecuritiesDebt

us-gaap:ProceedsFromSaleOfAvailableForSaleSecuritiesDebt


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value7211712567211439483426
Percentage of ProceedsFromSaleOfAvailableForSaleSecuritiesDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromStockOptionsExercised

us-gaap:ProceedsFromStockOptionsExercised


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value16000.0135000.066000.0209000.055000.021000.042000.0-40000.016000.069000.0
Percentage of ProceedsFromStockOptionsExercised100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromStockPlans

us-gaap:ProceedsFromStockPlans


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value0537000.00433000.00396000.0
Percentage of ProceedsFromStockPlans0.0100.00.0100.00.0100.0

us-gaap:ProceedsFromStockPlans us-gaap:PlanName

fixx:TwentyEighteenEmployeeStockPurchasePlan


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value0500000.00400000.00400000.0
Percentage of ProceedsFromStockPlans0.093.10.092.40.0101.0

us-gaap:PropertyPlantAndEquipmentDisposals

us-gaap:PropertyPlantAndEquipmentDisposals


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0.00.0130.00.00.00.10.00.00.0
Percentage of PropertyPlantAndEquipmentDisposals0.00.0100.00.00.00.0100.00.00.00.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value0.6540.63500.6320.6310.646800.566400.60120.05020.0085-0.05870.594
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum100.0100.00.0100.0100.0100.00.0100.00.0100.0100.0100.0100.0100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value0.6480.63200.6240.62690.640300.565600.528-0.007900.00510.5301
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum100.0100.00.0100.0100.0100.00.0100.00.0100.0100.00.0100.0100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value0.00540.017300.01940.02380.0260.00080.030.00150.02690.00090-0.00030.0231
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value0.00330.007400.01360.01950.024800.027700.02330.0028-0.0024-0.00220.0222
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum100.0100.00.0100.0100.0100.00.0100.00.0100.0100.0100.0100.0100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0500000.0500000.0800000.0200000.0400000.0200000.0600000.0600000.0400000.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue0.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-1.2512.47-1.8-0.42-0.6815.81.90.13-0.068.441.590.86-0.010.34
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans us-gaap:PlanName

us-gaap:StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans

fixx:TwentyEighteenEmployeeStockPurchasePlan


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value039471.0026923.0028311.0
Percentage of StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans0.0100.00.0100.00.0100.0

us-gaap:StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans us-gaap:StatementEquityComponents

us-gaap:CommonStock


None
Period End2020-03-312019-09-302019-03-31
Value39471.026923.028311.0
Percentage of StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans100.0100.0100.0

us-gaap:StockIssuedDuringPeriodSharesStockOptionsExercised

us-gaap:StockIssuedDuringPeriodSharesStockOptionsExercised


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value3576.034311.039568.043429.012404.018876.015754.019412.027680.026204.0
Percentage of StockIssuedDuringPeriodSharesStockOptionsExercised100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StockIssuedDuringPeriodSharesStockOptionsExercised us-gaap:StatementEquityComponents

us-gaap:CommonStock


None
Period End2020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value3576.034311.043429.012404.018876.015754.019412.011530.026204.0
Percentage of StockIssuedDuringPeriodSharesStockOptionsExercised100.0100.0100.0100.0100.0100.0100.041.7100.0

us-gaap:StockIssuedDuringPeriodValueEmployeeStockPurchasePlan

us-gaap:StockIssuedDuringPeriodValueEmployeeStockPurchasePlan


None
Period End2020-03-312019-09-302019-03-31
Value537000.0433000.0396000.0
Percentage of StockIssuedDuringPeriodValueEmployeeStockPurchasePlan100.0100.0100.0

us-gaap:StockIssuedDuringPeriodValueEmployeeStockPurchasePlan us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital


None
Period End2020-03-312019-09-302019-03-31
Value537000.0433000.0396000.0
Percentage of StockIssuedDuringPeriodValueEmployeeStockPurchasePlan100.0100.0100.0

us-gaap:StockIssuedDuringPeriodValueStockOptionsExercised

us-gaap:StockIssuedDuringPeriodValueStockOptionsExercised


None
Period End2020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value16000.0135000.0209000.055000.021000.041794.0-40000.016000.069000.0
Percentage of StockIssuedDuringPeriodValueStockOptionsExercised100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StockIssuedDuringPeriodValueStockOptionsExercised us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital


None
Period End2020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value16000.0135000.0209000.055000.021000.041800.0-40000.016000.069000.0
Percentage of StockIssuedDuringPeriodValueStockOptionsExercised100.0100.0100.0100.0100.0100.0100.0100.0100.0

fixx:AccruedExpensesAndOtherLiabilitiesCurrent

fixx:AccruedExpensesAndOtherLiabilitiesCurrent


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value9274000.06949000.07644000.07818000.05306000.03792000.05040000.03847800.02358400.02258000.02860000.0
Percentage of AccruedExpensesAndOtherLiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

fixx:AccruedResearchAndDevelopmentExpensesCurrent

fixx:AccruedResearchAndDevelopmentExpensesCurrent


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value4285000.03808000.02258000.03012000.01463000.01397000.01059000.0825490.0326400.0150000.0182500.0
Percentage of AccruedResearchAndDevelopmentExpensesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

fixx:AccruedUnvestedCommonStockSubjectToRepurchaseCurrent

fixx:AccruedUnvestedCommonStockSubjectToRepurchaseCurrent


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value21000.025000.037000.048000.076000.094000.0112000.0130060.0116800.0107140.0122550.0
Percentage of AccruedUnvestedCommonStockSubjectToRepurchaseCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

fixx:UnvestedCommonSharesSubjectToRepurchaseOutstanding

fixx:UnvestedCommonSharesSubjectToRepurchaseOutstanding


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value5113.06124.021666.072577.088681.0119700.0151290.0184000.0219750.0230960.0265100.0
Percentage of UnvestedCommonSharesSubjectToRepurchaseOutstanding100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccruedProfessionalFeesCurrent

us-gaap:AccruedProfessionalFeesCurrent


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value403000.0642000.0542000.0578000.0440000.0482000.0195000.0484360.0388270.01156500.01120000.0
Percentage of AccruedProfessionalFeesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AssetsFairValueDisclosure us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency

us-gaap:AssetsFairValueDisclosure

us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsRecurring


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value127143393655403111352844
Percentage of AssetsFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value78912222332401471822262198678
Percentage of AssetsFairValueDisclosure62.064.0563.2632.4436.1364.5574.31979.8612.5300.5176.7

us-gaap:AssetsFairValueDisclosure us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementsRecurring


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value206234262270295187214237254115122
Percentage of AssetsFairValueDisclosure162.0164.0663.2732.4536.1464.5674.32079.8712.5400.5276.7

us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax

us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-09-302018-06-30
Value11000.045000.0183000.0258000.0186000.016000.07139.02147.0
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax us-gaap:InvestmentType

us-gaap:CorporateDebtSecurities


None
Period End2020-06-302019-12-312019-09-302019-06-302019-03-312018-09-302018-06-30
Value5000.0128000.0210000.0146000.06000.06772.0813.0
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax45.569.981.478.537.594.937.9

us-gaap:USTreasurySecurities


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-06-30
Value6000.045000.045000.036000.029000.08000.055.0
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax54.5100.024.614.015.650.02.6

us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax

us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax


None
Period End2020-03-312019-12-312019-09-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value64000.004000.010000.077000.028017.050793.073308.0
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax100.00.0100.0100.0100.0100.0100.0100.0

us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax us-gaap:InvestmentType

us-gaap:CorporateDebtSecurities


None
Period End2020-03-312019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value64000.09000.050000.011505.035971.053474.049532.0
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax100.090.064.941.170.80.067.6

us-gaap:AvailableForSaleDebtSecuritiesAmortizedCostBasis

us-gaap:AvailableForSaleDebtSecuritiesAmortizedCostBasis


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value206234261269295187214237254122
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AvailableForSaleDebtSecuritiesAmortizedCostBasis us-gaap:CashAndCashEquivalents

us-gaap:MoneyMarketFunds


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value1271433936544031113544
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis61.761.015.113.718.621.514.84.814.036.1

us-gaap:AvailableForSaleDebtSecuritiesAmortizedCostBasis us-gaap:InvestmentType

us-gaap:AssetBackedSecurities


None
Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value4.5141116181919208.0992457.428021
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis1.95.74.35.79.69.18.27.90.06.1

us-gaap:CommercialPaper


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value6.99725412351567898853234
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis3.411.015.88.517.430.136.741.333.70.028.5

us-gaap:CorporateDebtSecurities


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value6.00745929279455454642126
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis2.919.235.334.227.024.525.422.925.20.022.0

us-gaap:USTreasurySecurities


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value651559643126295449248.940778
Percentage of AvailableForSaleDebtSecuritiesAmortizedCostBasis32.06.822.924.010.814.314.022.919.20.07.3

us-gaap:AvailableForSaleSecuritiesDebtSecurities

us-gaap:AvailableForSaleSecuritiesDebtSecurities


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value206234262270295187214237254122
Percentage of AvailableForSaleSecuritiesDebtSecurities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AvailableForSaleSecuritiesDebtSecurities us-gaap:CashAndCashEquivalents

us-gaap:MoneyMarketFunds


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value1271433936544031113544
Percentage of AvailableForSaleSecuritiesDebtSecurities61.761.015.113.718.621.514.84.814.036.1

us-gaap:AvailableForSaleSecuritiesDebtSecurities us-gaap:InvestmentType

us-gaap:AssetBackedSecurities


None
Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value4.5141116181919208.0905247.421703
Percentage of AvailableForSaleSecuritiesDebtSecurities1.95.74.35.79.69.18.27.90.06.1

us-gaap:CommercialPaper


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value6.99725412351567898853234
Percentage of AvailableForSaleSecuritiesDebtSecurities3.411.015.78.517.430.136.741.333.70.028.5

us-gaap:CorporateDebtSecurities


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value6.01245929279455454642126
Percentage of AvailableForSaleSecuritiesDebtSecurities2.919.235.334.327.124.525.422.925.10.022.0

us-gaap:USTreasurySecurities


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value651659643226295448248.92332
Percentage of AvailableForSaleSecuritiesDebtSecurities32.06.822.924.010.814.314.022.919.20.07.3

us-gaap:AvailableForSaleSecuritiesDebtSecuritiesCurrent

us-gaap:AvailableForSaleSecuritiesDebtSecuritiesCurrent


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value39912081921801471762011607078
Percentage of AvailableForSaleSecuritiesDebtSecuritiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AvailableForSaleSecuritiesDebtSecuritiesCurrent us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value399120819218014717620116078
Percentage of AvailableForSaleSecuritiesDebtSecuritiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AvailableForSaleSecuritiesDebtSecuritiesCurrent us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, us-gaap:InvestmentType

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring, us-gaap:AssetBackedSecurities


None
Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value4.5141116181919205.3926847.421703
Percentage of AvailableForSaleSecuritiesDebtSecuritiesCurrent4.97.16.09.412.311.19.712.67.69.5

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring, us-gaap:CommercialPaper


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value6.99725412351567298531834
Percentage of AvailableForSaleSecuritiesDebtSecuritiesCurrent17.928.319.812.028.538.341.148.733.026.744.7

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring, us-gaap:CorporateDebtSecurities


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value6.01245929279455454582126
Percentage of AvailableForSaleSecuritiesDebtSecuritiesCurrent15.449.344.348.244.331.230.927.036.430.334.4

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring, us-gaap:USTreasurySecurities


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value251659643126292928248.92332
Percentage of AvailableForSaleSecuritiesDebtSecuritiesCurrent66.617.528.733.717.718.217.014.618.035.311.4

us-gaap:AvailableForSaleSecuritiesDebtSecuritiesCurrent us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementsRecurring


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value399120819218014717620116078
Percentage of AvailableForSaleSecuritiesDebtSecuritiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AvailableForSaleSecuritiesDebtSecuritiesCurrent us-gaap:FairValueByMeasurementFrequency, us-gaap:InvestmentType

us-gaap:FairValueMeasurementsRecurring, us-gaap:AssetBackedSecurities


None
Period End2020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value4.5141116181919205.3926847.421703
Percentage of AvailableForSaleSecuritiesDebtSecuritiesCurrent4.97.16.09.412.311.19.712.67.69.5

us-gaap:FairValueMeasurementsRecurring, us-gaap:CommercialPaper


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value6.99725412351567298531834
Percentage of AvailableForSaleSecuritiesDebtSecuritiesCurrent17.928.319.812.028.538.341.148.733.026.744.7

us-gaap:FairValueMeasurementsRecurring, us-gaap:CorporateDebtSecurities


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value6.01245929279455454582126
Percentage of AvailableForSaleSecuritiesDebtSecuritiesCurrent15.449.344.348.244.331.230.927.036.430.334.4

us-gaap:FairValueMeasurementsRecurring, us-gaap:USTreasurySecurities


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value251659643126292928248.92332
Percentage of AvailableForSaleSecuritiesDebtSecuritiesCurrent66.617.528.733.717.718.217.014.618.035.311.4

us-gaap:CashAndCashEquivalentsFairValueDisclosure us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency

us-gaap:CashAndCashEquivalentsFairValueDisclosure

us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsRecurring


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value1271433936554031113544
Percentage of CashAndCashEquivalentsFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring


None
Period End2020-06-302019-12-312019-09-302019-06-302018-12-312018-09-302018-06-30
Value391441605.9742558
Percentage of CashAndCashEquivalentsFairValueDisclosure31.435.4111.7108.918.8218.6163.8

us-gaap:CashAndCashEquivalentsFairValueDisclosure us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, us-gaap:InvestmentType

us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsRecurring, us-gaap:MoneyMarketFunds


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value127143393654403111352844
Percentage of CashAndCashEquivalentsFairValueDisclosure100.0100.0100.0100.099.899.899.9100.0100.00.0100.0

us-gaap:FairValueInputsLevel2, us-gaap:FairValueMeasurementsRecurring, us-gaap:USTreasurySecurities


None
Period End2020-06-302018-09-302018-06-30
Value392520
Percentage of CashAndCashEquivalentsFairValueDisclosure31.4218.656.2

us-gaap:CashAndCashEquivalentsFairValueDisclosure us-gaap:FairValueByMeasurementFrequency

us-gaap:FairValueMeasurementsRecurring


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-31
Value16714353781154037369444
Percentage of CashAndCashEquivalentsFairValueDisclosure131.4100.0135.4211.7208.9100.0118.8318.6263.8100.0

us-gaap:CashAndCashEquivalentsFairValueDisclosure us-gaap:FairValueByMeasurementFrequency, us-gaap:InvestmentType

us-gaap:FairValueMeasurementsRecurring, us-gaap:MoneyMarketFunds


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value127143393654403111352844
Percentage of CashAndCashEquivalentsFairValueDisclosure100.0100.0100.0100.099.899.899.9100.0100.00.0100.0

us-gaap:FairValueMeasurementsRecurring, us-gaap:USTreasurySecurities


None
Period End2020-06-302019-09-302019-06-302019-03-312018-12-312018-09-302018-06-30
Value390.0090.0930.0690.0352520
Percentage of CashAndCashEquivalentsFairValueDisclosure31.40.00.20.20.1218.656.2

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value1681445578116423937964753
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ContractWithCustomerLiability us-gaap:CounterpartyName, us-gaap:TypeOfArrangement

us-gaap:ContractWithCustomerLiability

fixx:NovartisInstitutesOfBioMedicalResearchInc, us-gaap:CollaborativeArrangement


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-07-012018-04-012018-01-01
Value303031313131310.50.50.4
Percentage of ContractWithCustomerLiability100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ContractWithCustomerLiabilityNoncurrent

us-gaap:ContractWithCustomerLiabilityNoncurrent


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value29293030303030
Percentage of ContractWithCustomerLiabilityNoncurrent100.0100.0100.0100.0100.0100.0100.0

us-gaap:EmployeeRelatedLiabilitiesCurrent

us-gaap:EmployeeRelatedLiabilitiesCurrent


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value4312000.02254000.04551000.03738000.03039000.01640000.03370000.02407800.01527000.0844450.01435000.0
Percentage of EmployeeRelatedLiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingLeaseLiability

us-gaap:OperatingLeaseLiability


None
Period End2020-06-302020-03-312020-01-01
Value16172.251
Percentage of OperatingLeaseLiability100.0100.0100.0

us-gaap:RestrictedCash

us-gaap:RestrictedCash


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value1274000.01274000.01274000.01274000.01274000.01274000.01772000.01790000.01790000.01772600.01772600.0
Percentage of RestrictedCash100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RevenueRemainingPerformanceObligation us-gaap:CounterpartyName

us-gaap:RevenueRemainingPerformanceObligation

fixx:NovartisInstitutesOfBioMedicalResearchInc


None
Period End2020-06-302020-03-312019-12-312019-09-30
Value30303131
Percentage of RevenueRemainingPerformanceObligation100.0100.0100.0100.0

us-gaap:SecurityDepositLiability us-gaap:CreditFacility

us-gaap:SecurityDepositLiability

fixx:LettersOfCreditAndSecuredByRestrictedCash


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value1300000.01300000.01300000.01300000.01300000.01300000.01800000.01800000.01800000.01800000.01800000.0
Percentage of SecurityDepositLiability100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant us-gaap:PlanName

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant

fixx:TwentyEighteenEmployeeStockPurchasePlan


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value1084000.01084000.0672330.0672330.0699250.0699250.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant100.0100.0100.0100.0100.0100.0

fixx:TwoThousandEighteenIncentiveAwardPlan


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value2551000.02802700.01637100.02643300.02666300.02942700.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant235.3258.5243.5393.1381.3420.8

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue


None
Period End2020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value191933263055394034315.977162
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Line plots across dimensions of each concept


us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecurities
(None,)
None
us-gaap:AllocatedShareBasedCompensationExpense
us-gaap:IncomeStatementLocation
(None,)
None
us-gaap:StockholdersEquity
us-gaap:StatementEquityComponents
(None,)
None
us-gaap:PropertyPlantAndEquipmentGross
us-gaap:PropertyPlantAndEquipmentByType
(None,)
None
us-gaap:StockholdersEquity
us-gaap:StatementEquityComponents
(None,)
None