Consideration on sale of purchased assets gross.

No definition available.

Name:	agen_ConsiderationOnSaleOfPurchasedAssetsGross
Namespace Prefix:	agen_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Effective annual interest rate over life of royalty purchase agreement.

+ References

No definition available.

+ Details

Name:	agen_EffectiveAnnualInterestRateOverLifeOfRoyaltyPurchaseAgreement
Namespace Prefix:	agen_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Liability related to sale of future royalties and milestones.

+ References

No definition available.

+ Details

Name:	agen_LiabilityRelatedToSaleOfFutureRoyaltiesAndMilestones
Namespace Prefix:	agen_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Liability related to sale of future royalties and milestones.

+ References

No definition available.

+ Details

Name:	agen_LiabilityRelatedToSaleOfFutureRoyaltiesAndMilestonesLineItems
Namespace Prefix:	agen_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Non-cash interest expense related to sale of future royalties.

+ References

No definition available.

+ Details

Name:	agen_NonCashInterestExpenseRelatedToSaleOfFutureRoyalties
Namespace Prefix:	agen_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Noncash royalty revenue recognized.

+ References

No definition available.

+ Details

Name:	agen_NoncashRoyaltyRevenueRecognized
Namespace Prefix:	agen_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Percentage increase in synthetic royalty based on certain future events.

+ References

No definition available.

+ Details

Name:	agen_PercentageIncreaseInSyntheticRoyaltyBasedOnCertainFutureEvents
Namespace Prefix:	agen_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of purchase of worldwide rights to receive royalties.

+ References

No definition available.

+ Details

Name:	agen_PercentageOfPurchaseOfWorldwideRightsToReceiveRoyalties
Namespace Prefix:	agen_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of royalties receipts.

+ References

No definition available.

+ Details

Name:	agen_PercentageOfRoyaltiesReceipts
Namespace Prefix:	agen_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of sale of development, regulatory and commercial milestone payments eligible to receive.

+ References

No definition available.

+ Details

Name:	agen_PercentageOfSaleOfDevelopmentRegulatoryAndCommercialMilestonePaymentsEligibleToReceive
Namespace Prefix:	agen_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of synthetic royalty on worldwide net sales of purchased assets.

+ References

No definition available.

+ Details

Name:	agen_PercentageOfSyntheticRoyaltyOnWorldwideNetSalesOfPurchasedAssets
Namespace Prefix:	agen_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage reduction in amounts payable upon overall payments due exceeding specified return hurdle.

+ References

No definition available.

+ Details

Name:	agen_PercentageReductionInAmountsPayableUponOverallPaymentsDueExceedingSpecifiedReturnHurdle
Namespace Prefix:	agen_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Proceeds from purchase agreement gross.

+ References

No definition available.

+ Details

Name:	agen_ProceedsFromPurchaseAgreementGross
Namespace Prefix:	agen_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Proceeds from royalties sold.

+ References

No definition available.

+ Details

Name:	agen_ProceedsFromRoyaltiesSold
Namespace Prefix:	agen_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Prospective effective annual interest rate over life of royalty purchase agreement.

+ References

No definition available.

+ Details

Name:	agen_ProspectiveEffectiveAnnualInterestRateOverLifeOfRoyaltyPurchaseAgreement
Namespace Prefix:	agen_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Reimbursable expenses.

+ References

No definition available.

+ Details

Name:	agen_ReimbursableExpenses
Namespace Prefix:	agen_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Time-based option to invest, additional amount.

+ References

No definition available.

+ Details

Name:	agen_TimeBasedOptionToInvestAdditionalAmount
Namespace Prefix:	agen_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Exercise price per share or per unit of warrants or rights outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(4))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-3

+ Details

Name:	us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-3

+ Details

Name:	us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_TypeOfArrangementAxis=agen_AmendmentAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ClassOfWarrantOrRightAxis=agen_LigandWarrantMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=agen_HCRMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ContractWithCustomerDurationAxis=agen_GSKAgreementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=agen_RoyaltyPurchaseAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=agen_LigandPharmaceuticalsIncorporatedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementEquityComponentsAxis=us-gaap_CommonStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=agen_PurchaseAndSaleAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ContractWithCustomerDurationAxis=agen_CoveredLicenseAgreementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Liability Related to the Sale of Future Royalties and Milestones (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	3 Months Ended
	Jan. 19, 2018	May 31, 2024	Mar. 31, 2026	Jan. 31, 2026	Dec. 31, 2025
Liability Related To Sale Of Future Royalties And Milestones [Line Items]
Non-cash royalty revenue recognized			$ 29,145
Non-cash interest expense			13,520
Amendment Agreement [Member] \| Ligand Warrant [Member]
Liability Related To Sale Of Future Royalties And Milestones [Line Items]
Warrants, exercise price				$ 7.5	$ 17.3
HCR [Member] \| GSK Agreements [Member] \| Royalty Purchase Agreement [Member]
Liability Related To Sale Of Future Royalties And Milestones [Line Items]
Percentage of purchase of worldwide rights to receive royalties	100.00%
Gross proceeds received for royalty rights	$ 190,000
Non-cash royalty revenue recognized			29,100
Non-cash interest expense			$ 8,700
Effective annual interest rate			(20.00%)
Prospective effective annual interest rate			24.10%
Ligand Pharmaceuticals Incorporated [Member] \| Common Stock [Member]
Liability Related To Sale Of Future Royalties And Milestones [Line Items]
Warrants issued to purchase shars of common stock		867,052
Warrants, exercise price		$ 17.3
Ligand Pharmaceuticals Incorporated [Member] \| Purchase Agreement [Member]
Liability Related To Sale Of Future Royalties And Milestones [Line Items]
Non-cash interest expense			$ 4,900
Effective annual interest rate			21.00%
Liability related to sale of future royalties and milestones			$ 63,879
Prospective effective annual interest rate			21.40%
Percentage of synthetic royalty on worldwide net sales of purchased assets		2.625%
Percentage reduction in amounts payable upon overall payments due exceeding specified return hurdle		50.00%
Percentage increase in synthetic royalty based on certain future events		1.00%
Consideration on sale of purchased assets gross		$ 75,000
Reimbursable expenses		900
Time-based option to invest, additional amount		$ 25,000
Gross proceeds from purchase agreement			$ 75,000
Ligand Pharmaceuticals Incorporated [Member] \| Covered License Agreements [Member] \| Purchase Agreement [Member]
Liability Related To Sale Of Future Royalties And Milestones [Line Items]
Percentage of sale of development, regulatory and commercial milestone payments eligible to receive		31.875%
Percentage of royalties receipts		18.75%