XML 48 R34.htm IDEA: XBRL DOCUMENT
v3.26.1

FAIR VALUE MEASUREMENTS (Details) - USD ($) $ in Thousands | Mar. 31, 2026 | Dec. 31, 2025
--- | --- | ---
Assets: |  |
Marketable securities | $ 270,192 | $ 321,648
Total | 320,798 | 377,458
Liabilities: |  |
Sale of future royalties | 129,773 | 129,582
Total | 129,773 | 129,582
U.S. Treasury securities |  |
Assets: |  |
Marketable securities | 14,985 | 22,951
Government-sponsored enterprise securities |  |
Assets: |  |
Marketable securities | 2,959 |
Commercial paper |  |
Assets: |  |
Marketable securities | 71,557 | 84,382
Corporate notes |  |
Assets: |  |
Marketable securities | 173,648 | 209,253
Money market funds |  |
Assets: |  |
Cash, cash equivalents and restricted cash | 45,337 | 50,557
Certificate of deposit |  |
Assets: |  |
Cash, cash equivalents and restricted cash | 274 | 274
Municipal securities |  |
Assets: |  |
Cash, cash equivalents and restricted cash | 12,038 | 10,041
Level 1 |  |
Assets: |  |
Total | 45,611 | 50,831
Liabilities: |  |
Sale of future royalties | 0 | 0
Total | 0 | 0
Level 1 | U.S. Treasury securities |  |
Assets: |  |
Marketable securities | 0 | 0
Level 1 | Government-sponsored enterprise securities |  |
Assets: |  |
Marketable securities | 0 |
Level 1 | Commercial paper |  |
Assets: |  |
Marketable securities | 0 | 0
Level 1 | Corporate notes |  |
Assets: |  |
Marketable securities | 0 | 0
Level 1 | Money market funds |  |
Assets: |  |
Cash, cash equivalents and restricted cash | 45,337 | 50,557
Level 1 | Certificate of deposit |  |
Assets: |  |
Cash, cash equivalents and restricted cash | 274 | 274
Level 1 | Municipal securities |  |
Assets: |  |
Cash, cash equivalents and restricted cash | 0 | 0
Level 2 |  |
Assets: |  |
Total | 275,187 | 326,627
Liabilities: |  |
Sale of future royalties | 0 | 0
Total | 0 | 0
Level 2 | U.S. Treasury securities |  |
Assets: |  |
Marketable securities | 14,985 | 22,951
Level 2 | Government-sponsored enterprise securities |  |
Assets: |  |
Marketable securities | 2,959 |
Level 2 | Commercial paper |  |
Assets: |  |
Marketable securities | 71,557 | 84,382
Level 2 | Corporate notes |  |
Assets: |  |
Marketable securities | 173,648 | 209,253
Level 2 | Money market funds |  |
Assets: |  |
Cash, cash equivalents and restricted cash | 0 | 0
Level 2 | Certificate of deposit |  |
Assets: |  |
Cash, cash equivalents and restricted cash | 0 | 0
Level 2 | Municipal securities |  |
Assets: |  |
Cash, cash equivalents and restricted cash | 12,038 | 10,041
Level 3 |  |
Assets: |  |
Total | 0 | 0
Liabilities: |  |
Sale of future royalties | 129,773 | 129,582
Total | 129,773 | 129,582
Level 3 | U.S. Treasury securities |  |
Assets: |  |
Marketable securities | 0 | 0
Level 3 | Government-sponsored enterprise securities |  |
Assets: |  |
Marketable securities | 0 |
Level 3 | Commercial paper |  |
Assets: |  |
Marketable securities | 0 | 0
Level 3 | Corporate notes |  |
Assets: |  |
Marketable securities | 0 | 0
Level 3 | Money market funds |  |
Assets: |  |
Cash, cash equivalents and restricted cash | 0 | 0
Level 3 | Certificate of deposit |  |
Assets: |  |
Cash, cash equivalents and restricted cash | 0 | 0
Level 3 | Municipal securities |  |
Assets: |  |
Cash, cash equivalents and restricted cash | $ 0 | $ 0

X
- Definition Cash And Cash Equivalents And Restricted Cash, Fair Value Disclosure + References No definition available. + Details
Name: | gern_CashAndCashEquivalentsAndRestrictedCashFairValueDisclosure
Namespace Prefix: | gern_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Carrying value as of the balance sheet date of obligations incurred through that date and payable for royalties. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(15)(5)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 + Details
Name: | us-gaap_AccruedRoyaltiesCurrentAndNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Fair value portion of asset recognized for present right to economic benefit. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 100 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482078/820-10-55-100 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 + Details
Name: | us-gaap_AssetsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_AssetsFairValueDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479130/326-30-45-1 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value of financial and nonfinancial obligations. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 + Details
Name: | us-gaap_LiabilitiesFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_LiabilitiesFairValueDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_USTreasuryNotesSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_CommercialPaperMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_CorporateNoteSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CashAndCashEquivalentsAxis=us-gaap_MoneyMarketFundsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CashAndCashEquivalentsAxis=us-gaap_CertificatesOfDepositMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CashAndCashEquivalentsAxis=us-gaap_MunicipalBondsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |