Purchase Obligation, Written Notice Term

No definition available.

Name:	gern_PurchaseObligationWrittenNoticeTerm
Namespace Prefix:	gern_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Severance plan.

+ References

No definition available.

+ Details

Name:	gern_SeverancePlanLineItems
Namespace Prefix:	gern_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The total number of new claims filed pertaining to a loss contingency during the period.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 450
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483076/450-20-50-4

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 450
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483076/450-20-50-9

+ Details

Name:	us-gaap_LossContingencyNewClaimsFiledNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of plaintiffs that have filed claims pertaining to a loss contingency.

+ References

+ Details

Name:	us-gaap_LossContingencyNumberOfPlaintiffs
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of the recorded obligation to transfer funds in the future for fixed or minimum amounts or quantities of goods or services at fixed or minimum prices (for example, as in take-or-pay contracts or throughput contracts).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 440
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482648/440-10-50-6

+ Details

Name:	us-gaap_RecordedUnconditionalPurchaseObligation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

CONTINGENCIES AND UNCERTAINTIES (Details) $ in Millions			3 Months Ended
CONTINGENCIES AND UNCERTAINTIES (Details) $ in Millions	Apr. 16, 2025 lawsuit plaintiff	Mar. 14, 2025 lawsuit	Mar. 31, 2025 USD ($)
Severance Plan
Number of putative securities lawsuits		2
Noncancelable commercial purchase commitments \| $			$ 110.9
Purchase obligation, written notice term			180 days
Subsequent Event
Severance Plan
Number of putative securities lawsuits	3
Number of plaintiffs \| plaintiff	3