2024 Q1 Form 10-K Financial Statement

#000155837024002616 Filed on March 06, 2024

View on sec.gov

Income Statement

Concept 2024 Q1 2023 Q4 2023
Revenue $4.059M $2.878M $5.904M
YoY Change
Cost Of Revenue
YoY Change
Gross Profit
YoY Change
Gross Profit Margin
Selling, General & Admin $10.43M $13.38M $50.85M
YoY Change -18.95% 2.26% 14.36%
% of Gross Profit
Research & Development $14.34M $27.92M $93.62M
YoY Change -34.84% 34.2% -3.21%
% of Gross Profit
Depreciation & Amortization $1.300M $1.325M $5.300M
YoY Change 0.0% -1.56% 3.31%
% of Gross Profit
Operating Expenses $81.69M $41.30M $144.5M
YoY Change 134.31% 21.87% 2.33%
Operating Profit -$77.63M -$138.6M
YoY Change 122.66% -1.86%
Interest Expense $3.093M $3.235M $11.95M
YoY Change 11.58% 41.7% 163.06%
% of Operating Profit
Other Income/Expense, Net $3.093M $11.95M
YoY Change 11.58% 163.06%
Pretax Income -$74.54M -$35.19M -$126.6M
YoY Change 132.26% 8.58% -7.34%
Income Tax $0.00
% Of Pretax Income
Net Earnings -$74.50M -$35.19M -$126.6M
YoY Change 132.09% 8.58% -7.32%
Net Earnings / Revenue -1835.43% -1222.59% -2144.31%
Basic Earnings Per Share -$1.12 -$1.96
Diluted Earnings Per Share -$1.12 -$0.53 -$1.96
COMMON SHARES
Basic Shares Outstanding 66.48M 66.08M 64.48M
Diluted Shares Outstanding 66.43M 64.48M

Balance Sheet

Concept 2024 Q1 2023 Q4 2023
SHORT-TERM ASSETS
Cash & Short-Term Investments $219.3M $264.4M $264.4M
YoY Change -24.02% -5.28% -5.28%
Cash & Equivalents $35.53M $66.45M $66.45M
Short-Term Investments $183.8M $197.9M $197.9M
Other Short-Term Assets $7.548M $290.0K $4.294M
YoY Change 11.49% 11.97% -42.97%
Inventory
Prepaid Expenses
Receivables $0.00 $3.960M $3.960M
Other Receivables $0.00 $0.00 $0.00
Total Short-Term Assets $226.9M $272.6M $272.6M
YoY Change -34.2% -5.02% -5.02%
LONG-TERM ASSETS
Property, Plant & Equipment $18.59M $25.80M $95.65M
YoY Change -15.63% 16.13% 17.47%
Goodwill
YoY Change
Intangibles
YoY Change
Long-Term Investments $14.63M
YoY Change
Other Assets $253.0K $265.0K $6.489M
YoY Change -56.6% -84.4% -17.07%
Total Long-Term Assets $59.03M $102.1M $102.1M
YoY Change -31.9% 14.45% 14.45%
TOTAL ASSETS
Total Short-Term Assets $226.9M $272.6M $272.6M
Total Long-Term Assets $59.03M $102.1M $102.1M
Total Assets $285.9M $374.8M $374.8M
YoY Change -33.73% -0.4% -0.4%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable $1.482M $2.346M $2.346M
YoY Change -1.46% 254.38% 254.38%
Accrued Expenses $13.67M $24.24M $24.24M
YoY Change -8.65% 34.22% 34.22%
Deferred Revenue
YoY Change
Short-Term Debt $0.00 $0.00 $0.00
YoY Change
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities $28.31M $39.91M $39.91M
YoY Change 24.52% 108.43% 108.43%
LONG-TERM LIABILITIES
Long-Term Debt $0.00 $0.00 $0.00
YoY Change
Other Long-Term Liabilities $125.6M $131.7M $131.7M
YoY Change -3.06% 76.51% 76.51%
Total Long-Term Liabilities $125.6M $131.7M $131.7M
YoY Change -3.06% 76.51% 76.51%
TOTAL LIABILITIES
Total Short-Term Liabilities $28.31M $39.91M $39.91M
Total Long-Term Liabilities $125.6M $131.7M $131.7M
Total Liabilities $153.9M $171.6M $171.6M
YoY Change 1.06% 83.03% 83.03%
SHAREHOLDERS EQUITY
Retained Earnings -$645.9M -$571.4M
YoY Change 35.44% 28.47%
Common Stock $7.000K $7.000K
YoY Change 0.0% 16.67%
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity $132.0M $203.1M $203.1M
YoY Change
Total Liabilities & Shareholders Equity $285.9M $374.8M $374.8M
YoY Change -33.73% -0.4% -0.4%

Cashflow Statement

Concept 2024 Q1 2023 Q4 2023
OPERATING ACTIVITIES
Net Income -$74.50M -$35.19M -$126.6M
YoY Change 132.09% 8.58% -7.32%
Depreciation, Depletion And Amortization $1.300M $1.325M $5.300M
YoY Change 0.0% -1.56% 3.31%
Cash From Operating Activities -$31.70M -$24.98M -$52.75M
YoY Change 14.52% 8.59% -48.52%
INVESTING ACTIVITIES
Capital Expenditures $1.918M $4.580M $7.397M
YoY Change 154.04% 571.55% -15.95%
Acquisitions
YoY Change
Other Investing Activities $1.365M $2.666M -$2.301M
YoY Change -128.08% -115.05% -98.75%
Cash From Investing Activities -$553.0K -$1.914M -$9.698M
YoY Change -90.15% -89.6% -94.96%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities -125.0K 77.00K 35.82M
YoY Change -100.35% -7.23% 175.75%
NET CHANGE
Cash From Operating Activities -31.70M -24.98M -52.75M
Cash From Investing Activities -553.0K -1.914M -9.698M
Cash From Financing Activities -125.0K 77.00K 35.82M
Net Change In Cash -32.38M -26.81M -26.63M
YoY Change -1405.97% -35.1% -90.56%
FREE CASH FLOW
Cash From Operating Activities -$31.70M -$24.98M -$52.75M
Capital Expenditures $1.918M $4.580M $7.397M
Free Cash Flow -$33.62M -$29.56M -$60.14M
YoY Change 18.23% 24.8% -45.94%

Facts In Submission

Frame Concept Type Concept / XBRL Key Value Unit
CY2023 dei Entity Central Index Key
EntityCentralIndexKey
0001733294
CY2023 dei Document Fiscal Period Focus
DocumentFiscalPeriodFocus
FY
CY2023 dei Amendment Flag
AmendmentFlag
false
CY2023 us-gaap Earnings Per Share Diluted
EarningsPerShareDiluted
-1.96
CY2022 us-gaap Earnings Per Share Diluted
EarningsPerShareDiluted
-2.35
CY2021 us-gaap Earnings Per Share Diluted
EarningsPerShareDiluted
-2.12
CY2023 us-gaap Weighted Average Number Of Diluted Shares Outstanding
WeightedAverageNumberOfDilutedSharesOutstanding
64483520
CY2022 us-gaap Weighted Average Number Of Diluted Shares Outstanding
WeightedAverageNumberOfDilutedSharesOutstanding
58114893
CY2021 us-gaap Weighted Average Number Of Diluted Shares Outstanding
WeightedAverageNumberOfDilutedSharesOutstanding
56295409
CY2022Q4 us-gaap Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued
UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued
0
CY2023Q4 us-gaap Unrecognized Tax Benefits Income Tax Penalties And Interest Accrued
UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued
0
CY2023Q4 us-gaap Commitments And Contingencies
CommitmentsAndContingencies
CY2022Q4 us-gaap Commitments And Contingencies
CommitmentsAndContingencies
CY2023Q4 us-gaap Operating Lease Weighted Average Remaining Lease Term1
OperatingLeaseWeightedAverageRemainingLeaseTerm1
P11Y
CY2022Q4 us-gaap Preferred Stock Shares Outstanding
PreferredStockSharesOutstanding
0
CY2023Q4 us-gaap Preferred Stock Shares Outstanding
PreferredStockSharesOutstanding
0
CY2022Q4 us-gaap Common Stock Shares Issued
CommonStockSharesIssued
59505437
CY2023Q4 us-gaap Common Stock Shares Outstanding
CommonStockSharesOutstanding
66205550
CY2022Q4 us-gaap Operating Lease Weighted Average Remaining Lease Term1
OperatingLeaseWeightedAverageRemainingLeaseTerm1
P10Y
CY2023 us-gaap Restructuring Incurred Cost Statement Of Income Or Comprehensive Income Extensible Enumeration
RestructuringIncurredCostStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration
http://fasb.org/us-gaap/2023#GeneralAndAdministrativeExpense http://fasb.org/us-gaap/2023#ResearchAndDevelopmentExpense
CY2022 us-gaap Impairment Long Lived Asset Held For Use Statement Of Income Or Comprehensive Income Extensible Enumeration
ImpairmentLongLivedAssetHeldForUseStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration
http://fasb.org/us-gaap/2023#NonoperatingIncomeExpense
CY2023 us-gaap Impairment Long Lived Asset Held For Use Statement Of Income Or Comprehensive Income Extensible Enumeration
ImpairmentLongLivedAssetHeldForUseStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration
http://fasb.org/us-gaap/2023#NonoperatingIncomeExpense
CY2023 dei Document Type
DocumentType
10-K
CY2023 dei Document Annual Report
DocumentAnnualReport
true
CY2023 dei Document Period End Date
DocumentPeriodEndDate
2023-12-31
CY2023 dei Current Fiscal Year End Date
CurrentFiscalYearEndDate
--12-31
CY2023 dei Document Fiscal Year Focus
DocumentFiscalYearFocus
2023
CY2023 dei Document Transition Report
DocumentTransitionReport
false
CY2023 dei Entity File Number
EntityFileNumber
001-39319
CY2023 dei Entity Registrant Name
EntityRegistrantName
GENERATION BIO CO.
CY2023 dei Entity Incorporation State Country Code
EntityIncorporationStateCountryCode
DE
CY2023 dei Entity Tax Identification Number
EntityTaxIdentificationNumber
81-4301284
CY2023 dei Entity Address Address Line1
EntityAddressAddressLine1
301 Binney Street
CY2023 dei Entity Address City Or Town
EntityAddressCityOrTown
Cambridge
CY2023 dei Entity Address State Or Province
EntityAddressStateOrProvince
MA
CY2023 dei Entity Address Postal Zip Code
EntityAddressPostalZipCode
02142
CY2023 dei City Area Code
CityAreaCode
617
CY2023 dei Local Phone Number
LocalPhoneNumber
655-7500
CY2023 dei Security12b Title
Security12bTitle
Common Stock, $0.0001 Par Value
CY2023 dei Trading Symbol
TradingSymbol
GBIO
CY2023 dei Security Exchange Name
SecurityExchangeName
NASDAQ
CY2023 dei Entity Well Known Seasoned Issuer
EntityWellKnownSeasonedIssuer
No
CY2023 dei Entity Voluntary Filers
EntityVoluntaryFilers
No
CY2023 dei Entity Current Reporting Status
EntityCurrentReportingStatus
Yes
CY2023 dei Entity Interactive Data Current
EntityInteractiveDataCurrent
Yes
CY2023 dei Entity Filer Category
EntityFilerCategory
Non-accelerated Filer
CY2023 dei Entity Small Business
EntitySmallBusiness
true
CY2023 dei Entity Emerging Growth Company
EntityEmergingGrowthCompany
false
CY2023 dei Icfr Auditor Attestation Flag
IcfrAuditorAttestationFlag
false
CY2023 dei Entity Shell Company
EntityShellCompany
false
CY2023 dei Document Fin Stmt Error Correction Flag
DocumentFinStmtErrorCorrectionFlag
false
CY2023Q2 dei Entity Public Float
EntityPublicFloat
299400000
CY2024Q1 dei Entity Common Stock Shares Outstanding
EntityCommonStockSharesOutstanding
66477111
CY2023 ecd Non Rule10b51 Arr Adopted Flag
NonRule10b51ArrAdoptedFlag
false
CY2023 ecd Rule10b51 Arr Adopted Flag
Rule10b51ArrAdoptedFlag
false
CY2023 ecd Non Rule10b51 Arr Trmntd Flag
NonRule10b51ArrTrmntdFlag
false
CY2023 ecd Rule10b51 Arr Trmntd Flag
Rule10b51ArrTrmntdFlag
false
CY2023 dei Auditor Firm
AuditorFirmId
42
CY2023 dei Auditor Name
AuditorName
Ernst & Young LLP
CY2023 dei Auditor Location
AuditorLocation
Boston, Massachusetts
CY2023Q4 us-gaap Cash And Cash Equivalents At Carrying Value
CashAndCashEquivalentsAtCarryingValue
66446000
CY2022Q4 us-gaap Cash And Cash Equivalents At Carrying Value
CashAndCashEquivalentsAtCarryingValue
93171000
CY2023Q4 us-gaap Marketable Securities Current
MarketableSecuritiesCurrent
197918000
CY2022Q4 us-gaap Marketable Securities Current
MarketableSecuritiesCurrent
185920000
CY2023Q4 us-gaap Receivables Net Current
ReceivablesNetCurrent
3960000
CY2022Q4 us-gaap Receivables Net Current
ReceivablesNetCurrent
395000
CY2023Q4 us-gaap Prepaid Expense And Other Assets Current
PrepaidExpenseAndOtherAssetsCurrent
4294000
CY2022Q4 us-gaap Prepaid Expense And Other Assets Current
PrepaidExpenseAndOtherAssetsCurrent
7530000
CY2023Q4 us-gaap Assets Current
AssetsCurrent
272618000
CY2022Q4 us-gaap Assets Current
AssetsCurrent
287016000
CY2023Q4 us-gaap Property Plant And Equipment Net
PropertyPlantAndEquipmentNet
25799000
CY2022Q4 us-gaap Property Plant And Equipment Net
PropertyPlantAndEquipmentNet
22215000
CY2023Q4 us-gaap Operating Lease Right Of Use Asset
OperatingLeaseRightOfUseAsset
69852000
CY2022Q4 us-gaap Operating Lease Right Of Use Asset
OperatingLeaseRightOfUseAsset
59208000
CY2023Q4 us-gaap Restricted Cash Noncurrent
RestrictedCashNoncurrent
5791000
CY2022Q4 us-gaap Restricted Cash Noncurrent
RestrictedCashNoncurrent
5692000
CY2023Q4 us-gaap Deferred Costs
DeferredCosts
433000
CY2022Q4 us-gaap Deferred Costs
DeferredCosts
434000
CY2023Q4 us-gaap Other Assets Noncurrent
OtherAssetsNoncurrent
265000
CY2022Q4 us-gaap Other Assets Noncurrent
OtherAssetsNoncurrent
1699000
CY2023Q4 us-gaap Assets
Assets
374758000
CY2022Q4 us-gaap Assets
Assets
376264000
CY2023Q4 us-gaap Accounts Payable Current
AccountsPayableCurrent
2346000
CY2022Q4 us-gaap Accounts Payable Current
AccountsPayableCurrent
662000
CY2023Q4 us-gaap Accrued Liabilities And Other Liabilities
AccruedLiabilitiesAndOtherLiabilities
16529000
CY2022Q4 us-gaap Accrued Liabilities And Other Liabilities
AccruedLiabilitiesAndOtherLiabilities
11402000
CY2023Q4 us-gaap Deferred Revenue Current
DeferredRevenueCurrent
12919000
CY2022Q4 us-gaap Deferred Revenue Current
DeferredRevenueCurrent
0
CY2023Q4 us-gaap Operating Lease Liability Current
OperatingLeaseLiabilityCurrent
8120000
CY2022Q4 us-gaap Operating Lease Liability Current
OperatingLeaseLiabilityCurrent
7086000
CY2023Q4 us-gaap Liabilities Current
LiabilitiesCurrent
39914000
CY2022Q4 us-gaap Liabilities Current
LiabilitiesCurrent
19150000
CY2023Q4 us-gaap Deferred Revenue Noncurrent
DeferredRevenueNoncurrent
41942000
CY2022Q4 us-gaap Deferred Revenue Noncurrent
DeferredRevenueNoncurrent
0
CY2023Q4 us-gaap Operating Lease Liability Noncurrent
OperatingLeaseLiabilityNoncurrent
89774000
CY2022Q4 us-gaap Operating Lease Liability Noncurrent
OperatingLeaseLiabilityNoncurrent
74621000
CY2023Q4 us-gaap Liabilities
Liabilities
171630000
CY2022Q4 us-gaap Liabilities
Liabilities
93771000
CY2022Q4 us-gaap Preferred Stock Par Or Stated Value Per Share
PreferredStockParOrStatedValuePerShare
0.0001
CY2023Q4 us-gaap Preferred Stock Par Or Stated Value Per Share
PreferredStockParOrStatedValuePerShare
0.0001
CY2022Q4 us-gaap Preferred Stock Shares Authorized
PreferredStockSharesAuthorized
5000000
CY2023Q4 us-gaap Preferred Stock Shares Authorized
PreferredStockSharesAuthorized
5000000
CY2022Q4 us-gaap Preferred Stock Shares Issued
PreferredStockSharesIssued
0
CY2023Q4 us-gaap Preferred Stock Shares Issued
PreferredStockSharesIssued
0
CY2023Q4 us-gaap Preferred Stock Value
PreferredStockValue
0
CY2022Q4 us-gaap Preferred Stock Value
PreferredStockValue
0
CY2022Q4 us-gaap Common Stock Par Or Stated Value Per Share
CommonStockParOrStatedValuePerShare
0.0001
CY2023Q4 us-gaap Common Stock Par Or Stated Value Per Share
CommonStockParOrStatedValuePerShare
0.0001
CY2022Q4 us-gaap Common Stock Shares Authorized
CommonStockSharesAuthorized
150000000
CY2023Q4 us-gaap Common Stock Shares Authorized
CommonStockSharesAuthorized
150000000
CY2023Q4 us-gaap Common Stock Shares Issued
CommonStockSharesIssued
66205550
CY2022Q4 us-gaap Common Stock Shares Outstanding
CommonStockSharesOutstanding
59505437
CY2023Q4 us-gaap Common Stock Value
CommonStockValue
7000
CY2022Q4 us-gaap Common Stock Value
CommonStockValue
6000
CY2023Q4 us-gaap Additional Paid In Capital
AdditionalPaidInCapital
774224000
CY2022Q4 us-gaap Additional Paid In Capital
AdditionalPaidInCapital
727335000
CY2023Q4 us-gaap Accumulated Other Comprehensive Income Loss Net Of Tax
AccumulatedOtherComprehensiveIncomeLossNetOfTax
274000
CY2022Q4 us-gaap Accumulated Other Comprehensive Income Loss Net Of Tax
AccumulatedOtherComprehensiveIncomeLossNetOfTax
-83000
CY2023Q4 us-gaap Retained Earnings Accumulated Deficit
RetainedEarningsAccumulatedDeficit
-571377000
CY2022Q4 us-gaap Retained Earnings Accumulated Deficit
RetainedEarningsAccumulatedDeficit
-444765000
CY2023Q4 us-gaap Stockholders Equity
StockholdersEquity
203128000
CY2022Q4 us-gaap Stockholders Equity
StockholdersEquity
282493000
CY2023Q4 us-gaap Liabilities And Stockholders Equity
LiabilitiesAndStockholdersEquity
374758000
CY2022Q4 us-gaap Liabilities And Stockholders Equity
LiabilitiesAndStockholdersEquity
376264000
CY2023 us-gaap Revenue From Contract With Customer Excluding Assessed Tax
RevenueFromContractWithCustomerExcludingAssessedTax
5904000
CY2022 us-gaap Revenue From Contract With Customer Excluding Assessed Tax
RevenueFromContractWithCustomerExcludingAssessedTax
0
CY2021 us-gaap Revenue From Contract With Customer Excluding Assessed Tax
RevenueFromContractWithCustomerExcludingAssessedTax
0
CY2023 us-gaap Research And Development Expense
ResearchAndDevelopmentExpense
93617000
CY2022 us-gaap Research And Development Expense
ResearchAndDevelopmentExpense
96718000
CY2021 us-gaap Research And Development Expense
ResearchAndDevelopmentExpense
85247000
CY2023 us-gaap General And Administrative Expense
GeneralAndAdministrativeExpense
50850000
CY2022 us-gaap General And Administrative Expense
GeneralAndAdministrativeExpense
44464000
CY2021 us-gaap General And Administrative Expense
GeneralAndAdministrativeExpense
33854000
CY2023 us-gaap Operating Expenses
OperatingExpenses
144467000
CY2022 us-gaap Operating Expenses
OperatingExpenses
141182000
CY2021 us-gaap Operating Expenses
OperatingExpenses
119101000
CY2023 us-gaap Operating Income Loss
OperatingIncomeLoss
-138563000
CY2022 us-gaap Operating Income Loss
OperatingIncomeLoss
-141182000
CY2021 us-gaap Operating Income Loss
OperatingIncomeLoss
-119101000
CY2023 us-gaap Nonoperating Income Expense
NonoperatingIncomeExpense
11951000
CY2022 us-gaap Nonoperating Income Expense
NonoperatingIncomeExpense
4543000
CY2021 us-gaap Nonoperating Income Expense
NonoperatingIncomeExpense
-50000
CY2023 us-gaap Net Income Loss
NetIncomeLoss
-126612000
CY2022 us-gaap Net Income Loss
NetIncomeLoss
-136639000
CY2021 us-gaap Net Income Loss
NetIncomeLoss
-119151000
CY2023 us-gaap Earnings Per Share Basic
EarningsPerShareBasic
-1.96
CY2022 us-gaap Earnings Per Share Basic
EarningsPerShareBasic
-2.35
CY2021 us-gaap Earnings Per Share Basic
EarningsPerShareBasic
-2.12
CY2023 us-gaap Weighted Average Number Of Shares Outstanding Basic
WeightedAverageNumberOfSharesOutstandingBasic
64483520
CY2022 us-gaap Weighted Average Number Of Shares Outstanding Basic
WeightedAverageNumberOfSharesOutstandingBasic
58114893
CY2021 us-gaap Weighted Average Number Of Shares Outstanding Basic
WeightedAverageNumberOfSharesOutstandingBasic
56295409
CY2023 us-gaap Net Income Loss
NetIncomeLoss
-126612000
CY2022 us-gaap Net Income Loss
NetIncomeLoss
-136639000
CY2021 us-gaap Net Income Loss
NetIncomeLoss
-119151000
CY2023 us-gaap Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax
OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax
357000
CY2022 us-gaap Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax
OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax
-83000
CY2021 us-gaap Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax
OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax
-9000
CY2023 us-gaap Comprehensive Income Net Of Tax
ComprehensiveIncomeNetOfTax
-126255000
CY2022 us-gaap Comprehensive Income Net Of Tax
ComprehensiveIncomeNetOfTax
-136722000
CY2021 us-gaap Comprehensive Income Net Of Tax
ComprehensiveIncomeNetOfTax
-119160000
CY2020Q4 us-gaap Stockholders Equity
StockholdersEquity
268013000
CY2021 us-gaap Stock Issued During Period Value New Issues
StockIssuedDuringPeriodValueNewIssues
211286000
CY2021 us-gaap Stock Issued During Period Value Stock Options Exercised
StockIssuedDuringPeriodValueStockOptionsExercised
3257000
CY2021 us-gaap Stock Issued During Period Value Share Based Compensation
StockIssuedDuringPeriodValueShareBasedCompensation
493000
CY2021 us-gaap Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value
AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue
17857000
CY2021 us-gaap Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax
OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax
-9000
CY2021 us-gaap Profit Loss
ProfitLoss
-119151000
CY2021Q4 us-gaap Stockholders Equity
StockholdersEquity
381746000
CY2022 us-gaap Stock Issued During Period Value Stock Options Exercised
StockIssuedDuringPeriodValueStockOptionsExercised
628000
CY2022 us-gaap Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures
StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures
-581000
CY2022 us-gaap Stock Issued During Period Value Share Based Compensation
StockIssuedDuringPeriodValueShareBasedCompensation
632000
CY2022 us-gaap Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value
AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue
24452000
CY2022 us-gaap Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax
OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax
-83000
CY2022 us-gaap Profit Loss
ProfitLoss
-136639000
CY2022Q4 us-gaap Stockholders Equity
StockholdersEquity
282493000
CY2023 us-gaap Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures
StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures
-565000
CY2023 us-gaap Stock Issued During Period Value Share Based Compensation
StockIssuedDuringPeriodValueShareBasedCompensation
546000
CY2023 us-gaap Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value
AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue
24341000
CY2023 us-gaap Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax
OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax
357000
CY2023 us-gaap Profit Loss
ProfitLoss
-126612000
CY2023Q4 us-gaap Stockholders Equity
StockholdersEquity
203128000
CY2023 us-gaap Profit Loss
ProfitLoss
-126612000
CY2022 us-gaap Profit Loss
ProfitLoss
-136639000
CY2021 us-gaap Profit Loss
ProfitLoss
-119151000
CY2023 us-gaap Share Based Compensation
ShareBasedCompensation
24341000
CY2022 us-gaap Share Based Compensation
ShareBasedCompensation
24452000
CY2021 us-gaap Share Based Compensation
ShareBasedCompensation
17857000
CY2023 us-gaap Depreciation Depletion And Amortization
DepreciationDepletionAndAmortization
5263000
CY2022 us-gaap Depreciation Depletion And Amortization
DepreciationDepletionAndAmortization
5130000
CY2021 us-gaap Depreciation Depletion And Amortization
DepreciationDepletionAndAmortization
4532000
CY2023 us-gaap Investment Income Net Amortization Of Discount And Premium
InvestmentIncomeNetAmortizationOfDiscountAndPremium
9340000
CY2022 us-gaap Investment Income Net Amortization Of Discount And Premium
InvestmentIncomeNetAmortizationOfDiscountAndPremium
2289000
CY2021 us-gaap Investment Income Net Amortization Of Discount And Premium
InvestmentIncomeNetAmortizationOfDiscountAndPremium
-529000
CY2023 us-gaap Gain Loss On Sale Of Property Plant Equipment
GainLossOnSaleOfPropertyPlantEquipment
-27000
CY2022 us-gaap Gain Loss On Sale Of Property Plant Equipment
GainLossOnSaleOfPropertyPlantEquipment
-41000
CY2021 us-gaap Gain Loss On Sale Of Property Plant Equipment
GainLossOnSaleOfPropertyPlantEquipment
-237000
CY2023 us-gaap Asset Impairment Charges
AssetImpairmentCharges
39000
CY2022 us-gaap Asset Impairment Charges
AssetImpairmentCharges
5811000
CY2021 us-gaap Asset Impairment Charges
AssetImpairmentCharges
0
CY2023 gbio Increase Decrease In Tenant Improvements Allowance Receivable
IncreaseDecreaseInTenantImprovementsAllowanceReceivable
3565000
CY2022 gbio Increase Decrease In Tenant Improvements Allowance Receivable
IncreaseDecreaseInTenantImprovementsAllowanceReceivable
395000
CY2021 gbio Increase Decrease In Tenant Improvements Allowance Receivable
IncreaseDecreaseInTenantImprovementsAllowanceReceivable
0
CY2023 us-gaap Increase Decrease In Prepaid Deferred Expense And Other Assets
IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets
-3156000
CY2022 us-gaap Increase Decrease In Prepaid Deferred Expense And Other Assets
IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets
3489000
CY2021 us-gaap Increase Decrease In Prepaid Deferred Expense And Other Assets
IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets
-1367000
CY2023 gbio Increase Decrease In Operating Lease Right Of Use Assets
IncreaseDecreaseInOperatingLeaseRightOfUseAssets
10644000
CY2022 gbio Increase Decrease In Operating Lease Right Of Use Assets
IncreaseDecreaseInOperatingLeaseRightOfUseAssets
-5935000
CY2021 gbio Increase Decrease In Operating Lease Right Of Use Assets
IncreaseDecreaseInOperatingLeaseRightOfUseAssets
-3072000
CY2023 us-gaap Increase Decrease In Other Noncurrent Assets
IncreaseDecreaseInOtherNoncurrentAssets
-1433000
CY2022 us-gaap Increase Decrease In Other Noncurrent Assets
IncreaseDecreaseInOtherNoncurrentAssets
1295000
CY2021 us-gaap Increase Decrease In Other Noncurrent Assets
IncreaseDecreaseInOtherNoncurrentAssets
152000
CY2023 us-gaap Increase Decrease In Accounts Payable
IncreaseDecreaseInAccountsPayable
1087000
CY2022 us-gaap Increase Decrease In Accounts Payable
IncreaseDecreaseInAccountsPayable
-1386000
CY2021 us-gaap Increase Decrease In Accounts Payable
IncreaseDecreaseInAccountsPayable
1756000
CY2023 us-gaap Increase Decrease In Accrued Liabilities And Other Operating Liabilities
IncreaseDecreaseInAccruedLiabilitiesAndOtherOperatingLiabilities
4287000
CY2022 us-gaap Increase Decrease In Accrued Liabilities And Other Operating Liabilities
IncreaseDecreaseInAccruedLiabilitiesAndOtherOperatingLiabilities
795000
CY2021 us-gaap Increase Decrease In Accrued Liabilities And Other Operating Liabilities
IncreaseDecreaseInAccruedLiabilitiesAndOtherOperatingLiabilities
1833000
CY2023 us-gaap Increase Decrease In Deferred Revenue
IncreaseDecreaseInDeferredRevenue
41596000
CY2022 us-gaap Increase Decrease In Deferred Revenue
IncreaseDecreaseInDeferredRevenue
0
CY2021 us-gaap Increase Decrease In Deferred Revenue
IncreaseDecreaseInDeferredRevenue
0
CY2023 us-gaap Increase Decrease In Operating Lease Liability
IncreaseDecreaseInOperatingLeaseLiability
16187000
CY2022 us-gaap Increase Decrease In Operating Lease Liability
IncreaseDecreaseInOperatingLeaseLiability
881000
CY2021 us-gaap Increase Decrease In Operating Lease Liability
IncreaseDecreaseInOperatingLeaseLiability
-3701000
CY2023 us-gaap Net Cash Provided By Used In Operating Activities
NetCashProvidedByUsedInOperatingActivities
-52745000
CY2022 us-gaap Net Cash Provided By Used In Operating Activities
NetCashProvidedByUsedInOperatingActivities
-102448000
CY2021 us-gaap Net Cash Provided By Used In Operating Activities
NetCashProvidedByUsedInOperatingActivities
-91821000
CY2023 us-gaap Payments To Acquire Property Plant And Equipment
PaymentsToAcquirePropertyPlantAndEquipment
7397000
CY2022 us-gaap Payments To Acquire Property Plant And Equipment
PaymentsToAcquirePropertyPlantAndEquipment
8801000
CY2021 us-gaap Payments To Acquire Property Plant And Equipment
PaymentsToAcquirePropertyPlantAndEquipment
5958000
CY2023 us-gaap Proceeds From Sale Of Property Plant And Equipment
ProceedsFromSaleOfPropertyPlantAndEquipment
0
CY2022 us-gaap Proceeds From Sale Of Property Plant And Equipment
ProceedsFromSaleOfPropertyPlantAndEquipment
0
CY2021 us-gaap Proceeds From Sale Of Property Plant And Equipment
ProceedsFromSaleOfPropertyPlantAndEquipment
105000
CY2023 us-gaap Payments To Acquire Marketable Securities
PaymentsToAcquireMarketableSecurities
405301000
CY2022 us-gaap Payments To Acquire Marketable Securities
PaymentsToAcquireMarketableSecurities
323714000
CY2021 us-gaap Payments To Acquire Marketable Securities
PaymentsToAcquireMarketableSecurities
0
CY2023 us-gaap Proceeds From Sale And Maturity Of Marketable Securities
ProceedsFromSaleAndMaturityOfMarketableSecurities
403000000
CY2022 us-gaap Proceeds From Sale And Maturity Of Marketable Securities
ProceedsFromSaleAndMaturityOfMarketableSecurities
140000000
CY2021 us-gaap Proceeds From Sale And Maturity Of Marketable Securities
ProceedsFromSaleAndMaturityOfMarketableSecurities
198900000
CY2023 us-gaap Net Cash Provided By Used In Investing Activities
NetCashProvidedByUsedInInvestingActivities
-9698000
CY2022 us-gaap Net Cash Provided By Used In Investing Activities
NetCashProvidedByUsedInInvestingActivities
-192515000
CY2021 us-gaap Net Cash Provided By Used In Investing Activities
NetCashProvidedByUsedInInvestingActivities
193047000
CY2023 us-gaap Proceeds From Issuance Initial Public Offering
ProceedsFromIssuanceInitialPublicOffering
0
CY2022 us-gaap Proceeds From Issuance Initial Public Offering
ProceedsFromIssuanceInitialPublicOffering
0
CY2021 us-gaap Proceeds From Issuance Initial Public Offering
ProceedsFromIssuanceInitialPublicOffering
211876000
CY2023 us-gaap Payments Of Stock Issuance Costs
PaymentsOfStockIssuanceCosts
164000
CY2022 us-gaap Payments Of Stock Issuance Costs
PaymentsOfStockIssuanceCosts
50000
CY2021 us-gaap Payments Of Stock Issuance Costs
PaymentsOfStockIssuanceCosts
955000
CY2023 us-gaap Proceeds From Stock Options Exercised
ProceedsFromStockOptionsExercised
546000
CY2022 us-gaap Proceeds From Stock Options Exercised
ProceedsFromStockOptionsExercised
1260000
CY2021 us-gaap Proceeds From Stock Options Exercised
ProceedsFromStockOptionsExercised
3750000
CY2023 us-gaap Payments Related To Tax Withholding For Share Based Compensation
PaymentsRelatedToTaxWithholdingForShareBasedCompensation
565000
CY2022 us-gaap Payments Related To Tax Withholding For Share Based Compensation
PaymentsRelatedToTaxWithholdingForShareBasedCompensation
581000
CY2021 us-gaap Payments Related To Tax Withholding For Share Based Compensation
PaymentsRelatedToTaxWithholdingForShareBasedCompensation
0
CY2023 us-gaap Net Cash Provided By Used In Financing Activities
NetCashProvidedByUsedInFinancingActivities
35817000
CY2022 us-gaap Net Cash Provided By Used In Financing Activities
NetCashProvidedByUsedInFinancingActivities
12989000
CY2021 us-gaap Net Cash Provided By Used In Financing Activities
NetCashProvidedByUsedInFinancingActivities
214671000
CY2023 us-gaap Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect
CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect
-26626000
CY2022 us-gaap Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect
CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect
-281974000
CY2021 us-gaap Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect
CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect
315897000
CY2022Q4 us-gaap Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents
CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents
98863000
CY2021Q4 us-gaap Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents
CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents
380837000
CY2020Q4 us-gaap Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents
CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents
64940000
CY2023Q4 us-gaap Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents
CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents
72237000
CY2022Q4 us-gaap Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents
CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents
98863000
CY2021Q4 us-gaap Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents
CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents
380837000
CY2023 us-gaap Right Of Use Asset Obtained In Exchange For Operating Lease Liability
RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability
0
CY2022 us-gaap Right Of Use Asset Obtained In Exchange For Operating Lease Liability
RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability
0
CY2021 us-gaap Right Of Use Asset Obtained In Exchange For Operating Lease Liability
RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability
34806000
CY2023 us-gaap Capital Expenditures Incurred But Not Yet Paid
CapitalExpendituresIncurredButNotYetPaid
1461000
CY2022 us-gaap Capital Expenditures Incurred But Not Yet Paid
CapitalExpendituresIncurredButNotYetPaid
24000
CY2021 us-gaap Capital Expenditures Incurred But Not Yet Paid
CapitalExpendituresIncurredButNotYetPaid
1515000
CY2023 us-gaap Marketable Securities Unrealized Gain Loss
MarketableSecuritiesUnrealizedGainLoss
356000
CY2022 us-gaap Marketable Securities Unrealized Gain Loss
MarketableSecuritiesUnrealizedGainLoss
-83000
CY2021 us-gaap Marketable Securities Unrealized Gain Loss
MarketableSecuritiesUnrealizedGainLoss
-9000
CY2023 us-gaap Noncash Or Part Noncash Acquisition Payables Assumed1
NoncashOrPartNoncashAcquisitionPayablesAssumed1
0
CY2022 us-gaap Noncash Or Part Noncash Acquisition Payables Assumed1
NoncashOrPartNoncashAcquisitionPayablesAssumed1
0
CY2021 us-gaap Noncash Or Part Noncash Acquisition Payables Assumed1
NoncashOrPartNoncashAcquisitionPayablesAssumed1
55000
CY2023 dei Entity Incorporation Date Of Incorporation
EntityIncorporationDateOfIncorporation
2016-10-21
CY2021Q1 us-gaap Sale Of Stock Consideration Received On Transaction
SaleOfStockConsiderationReceivedOnTransaction
211300000
CY2023 us-gaap Net Income Loss
NetIncomeLoss
-126600000
CY2023Q4 us-gaap Retained Earnings Accumulated Deficit
RetainedEarningsAccumulatedDeficit
-571400000
CY2023 us-gaap Income Tax Examination Penalties And Interest Expense
IncomeTaxExaminationPenaltiesAndInterestExpense
0
CY2023 us-gaap Use Of Estimates
UseOfEstimates
<p style="font-family:'Times New Roman','Times','serif';font-size:10pt;font-style:italic;font-weight:bold;margin:0pt 0pt 12pt 0pt;">Use of estimates</p><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:justify;margin:0pt 0pt 12pt 0pt;">The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, the accrual of research and development expenses and stock-based compensation expense. We base our estimates on historical experience, known trends and other market-specific or other relevant factors that we believe to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates, as there are changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results may differ from those estimates or assumptions.</p>
CY2023 us-gaap Concentration Risk Credit Risk
ConcentrationRiskCreditRisk
<p style="font-family:'Times New Roman','Times','serif';font-size:10pt;font-style:italic;font-weight:bold;margin:0pt 0pt 12pt 0pt;">Concentrations of credit risk and of significant suppliers</p><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:justify;margin:0pt 0pt 12pt 0pt;">Financial instruments that potentially expose us to concentrations of credit risk consist primarily of cash, cash equivalents, and marketable securities. We believe that we are not exposed to significant credit risk due to the financial strength of the depository institutions in which our cash, cash equivalents, and marketable securities are held. We maintain our cash equivalents in money market funds that invest in U.S. treasury securities.  We have adopted an investment policy that limits the amounts that we may invest in the securities of a single issuer with the exclusion of the U.S. government. We have not experienced any credit losses. </p><p style="font-family:'Times New Roman','Times','serif';font-size:10pt;text-align:justify;margin:0pt 0pt 12pt 0pt;">We are dependent on a small number of third-party suppliers for our drug substance and drug product. In particular, we rely, and expect to continue to rely, on third-party suppliers for certain materials and components required for the production of any product candidates we may develop for our programs. These programs could be adversely affected by a significant interruption in the supply process.</p>
CY2022 us-gaap Impairment Of Long Lived Assets Held For Use
ImpairmentOfLongLivedAssetsHeldForUse
5800000
CY2021 us-gaap Impairment Of Long Lived Assets Held For Use
ImpairmentOfLongLivedAssetsHeldForUse
0
CY2023 us-gaap Number Of Operating Segments
NumberOfOperatingSegments
1
CY2023 us-gaap Effective Income Tax Rate Reconciliation Tax Settlements
EffectiveIncomeTaxRateReconciliationTaxSettlements
0.50
CY2022 us-gaap Income Tax Examination Penalties And Interest Expense
IncomeTaxExaminationPenaltiesAndInterestExpense
0
CY2023Q4 gbio Prepaid Research And Development Expenses Current
PrepaidResearchAndDevelopmentExpensesCurrent
2050000
CY2022Q4 gbio Prepaid Research And Development Expenses Current
PrepaidResearchAndDevelopmentExpensesCurrent
4555000
CY2023Q4 us-gaap Prepaid Insurance
PrepaidInsurance
680000
CY2022Q4 us-gaap Prepaid Insurance
PrepaidInsurance
1180000
CY2023Q4 gbio Prepaid Facilities Related Expenses Current
PrepaidFacilitiesRelatedExpensesCurrent
953000
CY2022Q4 gbio Prepaid Facilities Related Expenses Current
PrepaidFacilitiesRelatedExpensesCurrent
922000
CY2023Q4 gbio Prepaid Employee Compensation And Benefits Current
PrepaidEmployeeCompensationAndBenefitsCurrent
133000
CY2022Q4 gbio Prepaid Employee Compensation And Benefits Current
PrepaidEmployeeCompensationAndBenefitsCurrent
349000
CY2023Q4 gbio Interest Income Receivable Current
InterestIncomeReceivableCurrent
188000
CY2022Q4 gbio Interest Income Receivable Current
InterestIncomeReceivableCurrent
265000
CY2023Q4 us-gaap Other Assets Current
OtherAssetsCurrent
290000
CY2022Q4 us-gaap Other Assets Current
OtherAssetsCurrent
259000
CY2023Q4 us-gaap Prepaid Expense And Other Assets Current
PrepaidExpenseAndOtherAssetsCurrent
4294000
CY2022Q4 us-gaap Prepaid Expense And Other Assets Current
PrepaidExpenseAndOtherAssetsCurrent
7530000
CY2023Q4 us-gaap Property Plant And Equipment Gross
PropertyPlantAndEquipmentGross
45494000
CY2022Q4 us-gaap Property Plant And Equipment Gross
PropertyPlantAndEquipmentGross
36753000
CY2023Q4 us-gaap Accumulated Depreciation Depletion And Amortization Property Plant And Equipment
AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
19695000
CY2022Q4 us-gaap Accumulated Depreciation Depletion And Amortization Property Plant And Equipment
AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
14538000
CY2023Q4 us-gaap Property Plant And Equipment Net
PropertyPlantAndEquipmentNet
25799000
CY2022Q4 us-gaap Property Plant And Equipment Net
PropertyPlantAndEquipmentNet
22215000
CY2023 us-gaap Depreciation Depletion And Amortization
DepreciationDepletionAndAmortization
5300000
CY2022 us-gaap Depreciation Depletion And Amortization
DepreciationDepletionAndAmortization
5100000
CY2021 us-gaap Depreciation Depletion And Amortization
DepreciationDepletionAndAmortization
4500000
CY2023 us-gaap Lessee Operating Lease Existence Of Option To Extend
LesseeOperatingLeaseExistenceOfOptionToExtend
true
CY2023Q4 us-gaap Lessee Operating Lease Renewal Term
LesseeOperatingLeaseRenewalTerm
P5Y
CY2023Q4 gbio Letter Of Credit For Security Deposit
LetterOfCreditForSecurityDeposit
2100000
CY2022Q4 us-gaap Lessee Operating Lease Liability Payments Due
LesseeOperatingLeaseLiabilityPaymentsDue
104300000
CY2022Q4 us-gaap Lessee Operating Lease Term Of Contract
LesseeOperatingLeaseTermOfContract
P12Y
CY2021Q3 us-gaap Lessee Operating Lease Lease Not Yet Commenced Option To Extend
LesseeOperatingLeaseLeaseNotYetCommencedOptionToExtend
two
CY2021Q3 us-gaap Lessee Operating Lease Lease Not Yet Commenced Renewal Term1
LesseeOperatingLeaseLeaseNotYetCommencedRenewalTerm1
P5Y
CY2021Q3 gbio Initial Monthly Base Rent On Operating Lease
InitialMonthlyBaseRentOnOperatingLease
400000
CY2021Q3 gbio Construction Allowance In Operating Lease
ConstructionAllowanceInOperatingLease
26000000.0
CY2023 us-gaap Operating Lease Cost
OperatingLeaseCost
12585000
CY2022 us-gaap Operating Lease Cost
OperatingLeaseCost
13796000
CY2023 us-gaap Variable Lease Cost
VariableLeaseCost
2951000
CY2022 us-gaap Variable Lease Cost
VariableLeaseCost
2572000
CY2023 us-gaap Lease Cost
LeaseCost
15536000
CY2022 us-gaap Lease Cost
LeaseCost
16368000
CY2023 us-gaap Operating Lease Payments
OperatingLeasePayments
13400000
CY2022 us-gaap Operating Lease Payments
OperatingLeasePayments
9200000
CY2023Q4 us-gaap Operating Lease Weighted Average Discount Rate Percent
OperatingLeaseWeightedAverageDiscountRatePercent
0.075
CY2022Q4 us-gaap Operating Lease Weighted Average Discount Rate Percent
OperatingLeaseWeightedAverageDiscountRatePercent
0.074
CY2022Q4 us-gaap Accrued Professional Fees Current
AccruedProfessionalFeesCurrent
1047000
CY2023Q4 gbio Accrued Expense On Property And Equipment
AccruedExpenseOnPropertyAndEquipment
838000
CY2022Q4 gbio Accrued Expense On Property And Equipment
AccruedExpenseOnPropertyAndEquipment
0
CY2023Q4 us-gaap Other Liabilities Current
OtherLiabilitiesCurrent
406000
CY2022Q4 us-gaap Other Liabilities Current
OtherLiabilitiesCurrent
426000
CY2023Q4 us-gaap Lessee Operating Lease Liability Payments Due Next Twelve Months
LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths
15207000
CY2023Q4 us-gaap Lessee Operating Lease Liability Payments Due Year Two
LesseeOperatingLeaseLiabilityPaymentsDueYearTwo
15638000
CY2023Q4 us-gaap Lessee Operating Lease Liability Payments Due Year Three
LesseeOperatingLeaseLiabilityPaymentsDueYearThree
16094000
CY2023Q4 us-gaap Lessee Operating Lease Liability Payments Due Year Four
LesseeOperatingLeaseLiabilityPaymentsDueYearFour
16550000
CY2023Q4 us-gaap Lessee Operating Lease Liability Payments Due Year Five
LesseeOperatingLeaseLiabilityPaymentsDueYearFive
17058000
CY2023Q4 us-gaap Lessee Operating Lease Liability Payments Due After Year Five
LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive
56161000
CY2023Q4 us-gaap Lessee Operating Lease Liability Payments Due
LesseeOperatingLeaseLiabilityPaymentsDue
136708000
CY2023Q4 gbio Lessee Operating Lease Liability Undiscounted Unearned Tenant Improvements
LesseeOperatingLeaseLiabilityUndiscountedUnearnedTenantImprovements
39000
CY2023Q4 us-gaap Lessee Operating Lease Liability Undiscounted Excess Amount
LesseeOperatingLeaseLiabilityUndiscountedExcessAmount
38853000
CY2023Q4 us-gaap Operating Lease Liability
OperatingLeaseLiability
97894000
CY2023Q4 us-gaap Operating Lease Liability Current
OperatingLeaseLiabilityCurrent
8120000
CY2023Q4 us-gaap Operating Lease Liability Noncurrent
OperatingLeaseLiabilityNoncurrent
89774000
CY2023Q4 us-gaap Operating Lease Liability
OperatingLeaseLiability
97894000
CY2023Q4 us-gaap Employee Related Liabilities Current
EmployeeRelatedLiabilitiesCurrent
13208000
CY2022Q4 us-gaap Employee Related Liabilities Current
EmployeeRelatedLiabilitiesCurrent
7970000
CY2023Q4 gbio Accrued External Research And Development Expenses Current
AccruedExternalResearchAndDevelopmentExpensesCurrent
1169000
CY2022Q4 gbio Accrued External Research And Development Expenses Current
AccruedExternalResearchAndDevelopmentExpensesCurrent
1959000
CY2023Q4 us-gaap Accrued Professional Fees Current
AccruedProfessionalFeesCurrent
908000
CY2022Q4 us-gaap Deferred Tax Assets Deferred Income
DeferredTaxAssetsDeferredIncome
0
CY2023Q4 us-gaap Accrued Liabilities And Other Liabilities
AccruedLiabilitiesAndOtherLiabilities
16529000
CY2022Q4 us-gaap Accrued Liabilities And Other Liabilities
AccruedLiabilitiesAndOtherLiabilities
11402000
CY2023Q4 us-gaap Common Stock Shares Authorized
CommonStockSharesAuthorized
150000000
CY2023Q4 us-gaap Common Stock Par Or Stated Value Per Share
CommonStockParOrStatedValuePerShare
0.0001
CY2023Q4 us-gaap Preferred Stock Shares Authorized
PreferredStockSharesAuthorized
5000000
CY2023Q4 us-gaap Preferred Stock Par Or Stated Value Per Share
PreferredStockParOrStatedValuePerShare
0.0001
CY2021Q1 us-gaap Sale Of Stock Consideration Received On Transaction
SaleOfStockConsiderationReceivedOnTransaction
211300000
CY2021Q3 us-gaap Stock Issued During Period Shares New Issues
StockIssuedDuringPeriodSharesNewIssues
1795524
CY2021Q3 us-gaap Sale Of Stock Consideration Received On Transaction
SaleOfStockConsiderationReceivedOnTransaction
12300000
CY2023 gbio Number Of Vote Per Common Share
NumberOfVotePerCommonShare
1
CY2023 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate
ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
0.0388
CY2022 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate
ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
0.0208
CY2021 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate
ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
0.0081
CY2023 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate
ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
1.023
CY2022 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate
ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
0.912
CY2021 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Volatility Rate
ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
0.760
CY2023 us-gaap Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1
SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1
P6Y
CY2022 us-gaap Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1
SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1
P6Y
CY2021 us-gaap Sharebased Compensation Arrangement By Sharebased Payment Award Fair Value Assumptions Expected Term1
SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1
P6Y
CY2022Q4 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number
ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
8827322
CY2022Q4 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price
ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
13.15
CY2022 us-gaap Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2
SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2
P7Y11M19D
CY2022Q4 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value
ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue
55000
CY2023 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross
ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
3312016
CY2023 us-gaap Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price
ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice
3.20
CY2023 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period
ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod
1212540
CY2023 us-gaap Share Based Compensation Arrangements By Share Based Payment Award Options Forfeitures In Period Weighted Average Exercise Price
ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice
9.29
CY2023Q4 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number
ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
10926798
CY2023Q4 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price
ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
10.56
CY2023 us-gaap Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Remaining Contractual Term2
SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2
P6Y2M15D
CY2023Q4 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Intrinsic Value
ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue
404000
CY2023Q4 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Number
ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber
9967903
CY2023Q4 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Weighted Average Exercise Price
ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice
10.66
CY2023 us-gaap Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested And Expected To Vest Outstanding Weighted Average Remaining Contractual Term1
SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1
P6Y
CY2023Q4 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Outstanding Aggregate Intrinsic Value
ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue
387000
CY2023Q4 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Outstanding Number
ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber
5378652
CY2023Q4 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Outstanding Weighted Average Exercise Price
ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice
14.07
CY2023 us-gaap Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested And Expected To Vest Exercisable Weighted Average Remaining Contractual Term1
SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1
P5Y10D
CY2023Q4 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Aggregate Intrinsic Value
ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue
17000
CY2023Q4 us-gaap Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Intrinsic Value1
SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1
0
CY2022Q4 us-gaap Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Intrinsic Value1
SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1
500000
CY2021Q4 us-gaap Sharebased Compensation Arrangement By Sharebased Payment Award Options Exercisable Intrinsic Value1
SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1
19400000
CY2022Q4 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number
ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
959521
CY2022Q4 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value
ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
6.65
CY2023 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period
ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
895400
CY2023 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value
ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
4.47
CY2023 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period
ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
732448
CY2023 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value
ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
6.57
CY2023 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period
ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
102022
CY2023 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value
ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue
5.59
CY2023Q4 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number
ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
1020451
CY2023Q4 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value
ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
4.90
CY2023 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value
ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue
3300000
CY2022 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value
ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue
3500000
CY2021 us-gaap Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Total Fair Value
ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue
200000
CY2023 us-gaap Sharebased Compensation Arrangement By Sharebased Payment Award Purchase Price Of Common Stock Percent
SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent
0.85
CY2023 us-gaap Allocated Share Based Compensation Expense
AllocatedShareBasedCompensationExpense
24341000
CY2022 us-gaap Allocated Share Based Compensation Expense
AllocatedShareBasedCompensationExpense
24452000
CY2021 us-gaap Allocated Share Based Compensation Expense
AllocatedShareBasedCompensationExpense
17857000
CY2023Q4 us-gaap Deferred Tax Assets Other
DeferredTaxAssetsOther
13332000
CY2022Q4 us-gaap Deferred Tax Assets Other
DeferredTaxAssetsOther
10359000
CY2023Q4 us-gaap Deferred Tax Assets Net
DeferredTaxAssetsNet
197538000
CY2022Q4 us-gaap Deferred Tax Assets Net
DeferredTaxAssetsNet
157600000
CY2021 us-gaap Income Tax Expense Benefit
IncomeTaxExpenseBenefit
0
CY2022 us-gaap Income Tax Expense Benefit
IncomeTaxExpenseBenefit
0
CY2023 us-gaap Income Tax Expense Benefit
IncomeTaxExpenseBenefit
0
CY2023 us-gaap Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate
EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate
0.210
CY2022 us-gaap Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate
EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate
0.210
CY2021 us-gaap Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate
EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate
0.210
CY2023 us-gaap Effective Income Tax Rate Reconciliation State And Local Income Taxes
EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes
0.064
CY2022 us-gaap Effective Income Tax Rate Reconciliation State And Local Income Taxes
EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes
0.061
CY2021 us-gaap Effective Income Tax Rate Reconciliation State And Local Income Taxes
EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes
0.067
CY2023 us-gaap Effective Income Tax Rate Reconciliation Tax Credits Research
EffectiveIncomeTaxRateReconciliationTaxCreditsResearch
-0.043
CY2022 us-gaap Effective Income Tax Rate Reconciliation Tax Credits Research
EffectiveIncomeTaxRateReconciliationTaxCreditsResearch
-0.023
CY2021 us-gaap Effective Income Tax Rate Reconciliation Tax Credits Research
EffectiveIncomeTaxRateReconciliationTaxCreditsResearch
-0.024
CY2023 us-gaap Effective Income Tax Rate Reconciliation Nondeductible Expense Share Based Compensation Cost
EffectiveIncomeTaxRateReconciliationNondeductibleExpenseShareBasedCompensationCost
-0.019
CY2022 us-gaap Effective Income Tax Rate Reconciliation Nondeductible Expense Share Based Compensation Cost
EffectiveIncomeTaxRateReconciliationNondeductibleExpenseShareBasedCompensationCost
-0.009
CY2021 us-gaap Effective Income Tax Rate Reconciliation Nondeductible Expense Share Based Compensation Cost
EffectiveIncomeTaxRateReconciliationNondeductibleExpenseShareBasedCompensationCost
0.017
CY2023 us-gaap Effective Income Tax Rate Reconciliation Change In Deferred Tax Assets Valuation Allowance
EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance
-0.298
CY2022 us-gaap Effective Income Tax Rate Reconciliation Change In Deferred Tax Assets Valuation Allowance
EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance
-0.285
CY2021 us-gaap Effective Income Tax Rate Reconciliation Change In Deferred Tax Assets Valuation Allowance
EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance
-0.318
CY2023 us-gaap Effective Income Tax Rate Continuing Operations
EffectiveIncomeTaxRateContinuingOperations
0
CY2022 us-gaap Effective Income Tax Rate Continuing Operations
EffectiveIncomeTaxRateContinuingOperations
0
CY2021 us-gaap Effective Income Tax Rate Continuing Operations
EffectiveIncomeTaxRateContinuingOperations
0
CY2023Q4 us-gaap Deferred Tax Assets Operating Loss Carryforwards
DeferredTaxAssetsOperatingLossCarryforwards
96939000
CY2022Q4 us-gaap Deferred Tax Assets Operating Loss Carryforwards
DeferredTaxAssetsOperatingLossCarryforwards
89546000
CY2023Q4 us-gaap Deferred Tax Assets Tax Credit Carryforwards Research
DeferredTaxAssetsTaxCreditCarryforwardsResearch
20836000
CY2022Q4 us-gaap Deferred Tax Assets Tax Credit Carryforwards Research
DeferredTaxAssetsTaxCreditCarryforwardsResearch
15368000
CY2023Q4 gbio Deferred Tax Assets Operating Lease Liability
DeferredTaxAssetsOperatingLeaseLiability
26745000
CY2022Q4 gbio Deferred Tax Assets Operating Lease Liability
DeferredTaxAssetsOperatingLeaseLiability
22322000
CY2023Q4 gbio Deferred Tax Assets Capitalized Research And Development Costs
DeferredTaxAssetsCapitalizedResearchAndDevelopmentCosts
36345000
CY2022Q4 gbio Deferred Tax Assets Capitalized Research And Development Costs
DeferredTaxAssetsCapitalizedResearchAndDevelopmentCosts
20005000
CY2023Q4 us-gaap Deferred Tax Assets Deferred Income
DeferredTaxAssetsDeferredIncome
3341000
CY2023Q4 us-gaap Deferred Tax Liabilities Leasing Arrangements
DeferredTaxLiabilitiesLeasingArrangements
19084000
CY2022Q4 us-gaap Deferred Tax Liabilities Leasing Arrangements
DeferredTaxLiabilitiesLeasingArrangements
16176000
CY2023Q4 us-gaap Deferred Tax Liabilities Property Plant And Equipment
DeferredTaxLiabilitiesPropertyPlantAndEquipment
2912000
CY2022Q4 us-gaap Deferred Tax Liabilities Property Plant And Equipment
DeferredTaxLiabilitiesPropertyPlantAndEquipment
3566000
CY2023Q4 us-gaap Deferred Income Tax Liabilities
DeferredIncomeTaxLiabilities
21996000
CY2022Q4 us-gaap Deferred Income Tax Liabilities
DeferredIncomeTaxLiabilities
19742000
CY2023Q4 us-gaap Deferred Tax Assets Valuation Allowance
DeferredTaxAssetsValuationAllowance
175542000
CY2022Q4 us-gaap Deferred Tax Assets Valuation Allowance
DeferredTaxAssetsValuationAllowance
137858000
CY2023Q4 us-gaap Deferred Tax Assets Liabilities Net
DeferredTaxAssetsLiabilitiesNet
0
CY2022Q4 us-gaap Deferred Tax Assets Liabilities Net
DeferredTaxAssetsLiabilitiesNet
0
CY2023 gbio Tax Credit Carryforward Expiration Year
TaxCreditCarryforwardExpirationYear
2036
CY2023Q4 us-gaap Operating Loss Carryforwards
OperatingLossCarryforwards
344800000
CY2023 gbio Percentage On Annual Taxable Income
PercentageOnAnnualTaxableIncome
0.80
CY2023 gbio Operating Loss Carryforwards Expiration Year
OperatingLossCarryforwardsExpirationYear
2036
CY2023Q4 us-gaap Tax Credit Carryforward Amount
TaxCreditCarryforwardAmount
8000000.0
CY2023 gbio Percentage Of Change In Ownership
PercentageOfChangeInOwnership
0.50
CY2023Q4 us-gaap Deferred Tax Assets Operating Loss Carryforwards Subject To Expiration
DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration
700000
CY2022Q4 us-gaap Deferred Tax Assets Valuation Allowance
DeferredTaxAssetsValuationAllowance
137858000
CY2021Q4 us-gaap Deferred Tax Assets Valuation Allowance
DeferredTaxAssetsValuationAllowance
98902000
CY2023 us-gaap Tax Adjustments Settlements And Unusual Provisions
TaxAdjustmentsSettlementsAndUnusualProvisions
37684000
CY2022 us-gaap Tax Adjustments Settlements And Unusual Provisions
TaxAdjustmentsSettlementsAndUnusualProvisions
38956000
CY2023Q4 us-gaap Deferred Tax Assets Valuation Allowance
DeferredTaxAssetsValuationAllowance
175542000
CY2022Q4 us-gaap Deferred Tax Assets Valuation Allowance
DeferredTaxAssetsValuationAllowance
137858000
CY2023 gbio Unrecognized Tax Benefits Of Income Tax Rate
UnrecognizedTaxBenefitsOfIncomeTaxRate
0.50
CY2022Q4 us-gaap Unrecognized Tax Benefits
UnrecognizedTaxBenefits
0
CY2023Q4 us-gaap Unrecognized Tax Benefits
UnrecognizedTaxBenefits
0
CY2023 gbio Deferred Tax Assets Operating Loss Carryforwards Reduction
DeferredTaxAssetsOperatingLossCarryforwardsReduction
59800000
CY2023 us-gaap Defined Contribution Plan Employer Matching Contribution Percent
DefinedContributionPlanEmployerMatchingContributionPercent
0.04
CY2023 us-gaap Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount
AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
11947249
CY2022 us-gaap Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount
AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
9786843
CY2021 us-gaap Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount
AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
6229291
CY2023Q4 us-gaap Restructuring And Related Cost Number Of Positions Eliminated Period Percent
RestructuringAndRelatedCostNumberOfPositionsEliminatedPeriodPercent
0.40
CY2023 us-gaap Restructuring Charges
RestructuringCharges
7025000
CY2023 us-gaap Payments For Restructuring
PaymentsForRestructuring
1222000
CY2023 us-gaap Restructuring Reserve Settled Without Cash2
RestructuringReserveSettledWithoutCash2
512000
CY2023Q4 us-gaap Restructuring Reserve
RestructuringReserve
5291000
CY2023 us-gaap Restructuring And Related Cost Incurred Cost
RestructuringAndRelatedCostIncurredCost
7000000.0
CY2023Q4 us-gaap Restructuring And Related Cost Expected Cost1
RestructuringAndRelatedCostExpectedCost1
400000

Files In Submission

Name View Source Status
0001558370-24-002616-index-headers.html Edgar Link pending
0001558370-24-002616-index.html Edgar Link pending
0001558370-24-002616.txt Edgar Link pending
0001558370-24-002616-xbrl.zip Edgar Link pending
Financial_Report.xlsx Edgar Link pending
gbio-20231231.xsd Edgar Link pending
gbio-20231231x10k.htm Edgar Link pending
gbio-20231231x10k005.jpg Edgar Link pending
gbio-20231231x10k006.jpg Edgar Link pending
gbio-20231231xex19d1.htm Edgar Link pending
gbio-20231231xex21d1.htm Edgar Link pending
gbio-20231231xex23d1.htm Edgar Link pending
gbio-20231231xex31d1.htm Edgar Link pending
gbio-20231231xex31d2.htm Edgar Link pending
gbio-20231231xex32d1.htm Edgar Link pending
gbio-20231231xex32d2.htm Edgar Link pending
gbio-20231231xex97d1.htm Edgar Link pending
MetaLinks.json Edgar Link pending
R1.htm Edgar Link pending
R10.htm Edgar Link pending
R11.htm Edgar Link pending
R12.htm Edgar Link pending
R13.htm Edgar Link pending
R14.htm Edgar Link pending
R15.htm Edgar Link pending
R16.htm Edgar Link pending
R17.htm Edgar Link pending
FilingSummary.xml Edgar Link unprocessable
gbio-20231231_cal.xml Edgar Link unprocessable
gbio-20231231_def.xml Edgar Link unprocessable
gbio-20231231_lab.xml Edgar Link unprocessable
gbio-20231231_pre.xml Edgar Link unprocessable
gbio-20231231x10k_htm.xml Edgar Link completed
R18.htm Edgar Link pending
R19.htm Edgar Link pending
R2.htm Edgar Link pending
R20.htm Edgar Link pending
R21.htm Edgar Link pending
R22.htm Edgar Link pending
R23.htm Edgar Link pending
R24.htm Edgar Link pending
R25.htm Edgar Link pending
R26.htm Edgar Link pending
R27.htm Edgar Link pending
R28.htm Edgar Link pending
R29.htm Edgar Link pending
R3.htm Edgar Link pending
R30.htm Edgar Link pending
R31.htm Edgar Link pending
R32.htm Edgar Link pending
R33.htm Edgar Link pending
R34.htm Edgar Link pending
R35.htm Edgar Link pending
R36.htm Edgar Link pending
R37.htm Edgar Link pending
R38.htm Edgar Link pending
R39.htm Edgar Link pending
R4.htm Edgar Link pending
R40.htm Edgar Link pending
R41.htm Edgar Link pending
R42.htm Edgar Link pending
R43.htm Edgar Link pending
R44.htm Edgar Link pending
R45.htm Edgar Link pending
R46.htm Edgar Link pending
R47.htm Edgar Link pending
R48.htm Edgar Link pending
R49.htm Edgar Link pending
R5.htm Edgar Link pending
R50.htm Edgar Link pending
R51.htm Edgar Link pending
R52.htm Edgar Link pending
R53.htm Edgar Link pending
R54.htm Edgar Link pending
R55.htm Edgar Link pending
R56.htm Edgar Link pending
R57.htm Edgar Link pending
R58.htm Edgar Link pending
R59.htm Edgar Link pending
R6.htm Edgar Link pending
R60.htm Edgar Link pending
R61.htm Edgar Link pending
R62.htm Edgar Link pending
R63.htm Edgar Link pending
R64.htm Edgar Link pending
R65.htm Edgar Link pending
R66.htm Edgar Link pending
R67.htm Edgar Link pending
R68.htm Edgar Link pending
R69.htm Edgar Link pending
R7.htm Edgar Link pending
R70.htm Edgar Link pending
R71.htm Edgar Link pending
R8.htm Edgar Link pending
R9.htm Edgar Link pending
report.css Edgar Link pending
Show.js Edgar Link pending