XML 38 R28.htm IDEA: XBRL DOCUMENT
v3.23.1

DEBT - Additional Information (Details) - Hercules and Silicon Valley Bank [Member] - USD ($) | Jun. 30, 2022 | Jun. 01, 2022 | Mar. 31, 2023 | Sep. 30, 2020
--- | --- | --- | --- | ---
Debt Instrument [Line Items] |  |  |  |
Maximum borrowing capacity under term loan | $ 125,000,000 |  |  | $ 75,000,000
Principal amount outstanding under term loan |  |  | $ 50,000,000 |
Available remaining loan committed principal |  |  | 55,000,000 |
Carrying value of term loan, net |  |  | 51,399,000 |
Unamortized debt discount and issuance costs |  |  | 556,000 |
Accrued end of term charge |  |  | $ 1,955,000 |
Prepayment charge (as a percentage) | 1.50% |  |  |
Charge for prepayment occurring 36 months after effective date | $ 0 |  |  |
Description of term loan payment terms | Under the Loan Agreement, if we choose to prepay the principal with respect to any future draw down after the Effective Date, any such prepayment within the first 36 months after the Effective Date will be subject to a prepayment charge equal to 1.5% of the principal amount prepaid. No prepayment charge will be assessed for any prepayment occurring more than 36 months after the Effective Date. |  |  |
Minimum cash balance as a percentage of loan amount outstanding |  | 50.00% |  |
Debt covenant minimum cash balance |  | $ 30,000,000 |  |
Tranche One [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Maximum borrowing capacity under term loan | $ 10,000,000 |  |  |
Start date to borrow under a tranche for a debt instrument | Jan. 01, 2023 |  |  |
Expiration date to borrow under a tranche for a debt instrument | Dec. 15, 2023 |  |  |
Tranche Two [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Maximum borrowing capacity under term loan | $ 20,000,000 |  |  |
Start date to borrow under a tranche for a debt instrument | Sep. 15, 2023 |  |  |
Expiration date to borrow under a tranche for a debt instrument | Sep. 15, 2024 |  |  |
Tranche Three [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Maximum borrowing capacity under term loan | $ 25,000,000 |  |  |
Expiration date to borrow under a tranche for a debt instrument | Dec. 31, 2024 |  |  |
Option One Min Cash Debt Covenant [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Minimum cash balance as a percentage of loan amount outstanding | 40.00% |  |  |
Option Two Min Cash Debt Covenant [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Minimum cash balance as a percentage of loan amount outstanding | 25.00% |  |  |
Minimum market capitalization requirement for option | $ 750,000,000 |  |  |
Option Three Min Cash Debt Covenant [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Minimum cash balance requirement to be met as a percentage of six-month product revenue against forecast | 70.00% |  |  |
Minimum percentage of net product revenues maintenance period | 6 months |  |  |

X
- Definition Accrued end of term charges. + References No definition available. + Details
Name: | gern_AccruedEndOfTermCharges
Namespace Prefix: | gern_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition First date to available to drawdown any amount under a tranche. + References No definition available. + Details
Name: | gern_BorrowingAvailableStartDate
Namespace Prefix: | gern_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Debt Covenant Minimum Cash Balance + References No definition available. + Details
Name: | gern_DebtCovenantMinimumCashBalance
Namespace Prefix: | gern_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Percentage of loan amount outstanding to be held as minimum cash balance under debt covenant. + References No definition available. + Details
Name: | gern_DebtCovenantMinimumCashBalancePercentageOfLoanAmount
Namespace Prefix: | gern_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Minimum percentage of six-month product revenue forecast to satisfy minimum cash balance debt covenant. + References No definition available. + Details
Name: | gern_DebtCovenantPercentageOfProductRevenueAgainstForecast
Namespace Prefix: | gern_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Prepayment charge assessed upon debt prepayment occurring 36 months after June 30, 2022 under second amendment. + References No definition available. + Details
Name: | gern_DollarPrepaymentCharge36MonthsAfterEffectiveDate
Namespace Prefix: | gern_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Last date to drawdown any amounts under a tranche. + References No definition available. + Details
Name: | gern_ExpiryDateOfTranche
Namespace Prefix: | gern_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Minimum market capitalization required for this option to be available to meet the minimum cash balance debt covenant. + References No definition available. + Details
Name: | gern_MarketCapMinimumToUseOptionTwo
Namespace Prefix: | gern_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Minimum percentage of net product revenues maintenance period. + References No definition available. + Details
Name: | gern_MinimumPercentageOfNetProductRevenuesMaintenancePeriod
Namespace Prefix: | gern_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of prepayment amount to be paid upon prepayment under debt instrument. + References No definition available. + Details
Name: | gern_PercentageOfPrepaymentCharge
Namespace Prefix: | gern_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b)(1) -URI https://asc.fasb.org/extlink&oid=123466204&loc=SL6031897-161870 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(16)) -URI https://asc.fasb.org/extlink&oid=126734703&loc=d3e572229-122910 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI https://asc.fasb.org/extlink&oid=126897435&loc=d3e534808-122878 + Details
Name: | us-gaap_DebtInstrumentCarryingAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Description of the payment terms of the debt instrument (for example, whether periodic payments include principal and frequency of payments) and discussion about any contingencies associated with the payment. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(3)) -URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 470 -Section 50 -Paragraph 3 -Subparagraph (c) -URI https://asc.fasb.org/extlink&oid=123599511&loc=d3e64711-112823 + Details
Name: | us-gaap_DebtInstrumentPaymentTerms
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of unused borrowing capacity under the long-term financing arrangement that is available to the entity as of the balance sheet date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(b)) -URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount, excluding unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b)(3) -URI https://asc.fasb.org/extlink&oid=123466204&loc=SL6031897-161870 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 55 -Paragraph 69C -URI https://asc.fasb.org/extlink&oid=123466577&loc=SL123495737-112612 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)) -URI https://asc.fasb.org/extlink&oid=126734703&loc=d3e572229-122910 Reference 4: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 55 -Paragraph 69B -URI https://asc.fasb.org/extlink&oid=123466577&loc=SL123495735-112612 Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI https://asc.fasb.org/extlink&oid=126897435&loc=d3e534808-122878 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 1D -Subparagraph (b) -URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495340-112611 Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_LongTermDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset. + References No definition available. + Details
Name: | us-gaap_UnamortizedDebtIssuanceExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_DebtInstrumentAxis=gern_HerculesAndSiliconValleyBankMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CreditFacilityAxis=gern_TrancheOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CreditFacilityAxis=gern_TrancheTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CreditFacilityAxis=gern_TrancheThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CreditFacilityAxis=gern_OptionOneMinCashDebtCovenantMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CreditFacilityAxis=gern_OptionTwoMinCashDebtCovenantMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CreditFacilityAxis=gern_OptionThreeMinCashDebtCovenantMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |