Class of warrant expiration date.

No definition available.

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- Definition

Debt discount amortization period.

+ References

No definition available.

+ Details

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- Definition

Debt instrument, debt default provisions, face amount.

+ References

No definition available.

+ Details

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- Definition

Debt instrument period for computation of interest rate.

+ References

No definition available.

+ Details

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- Definition

Non cash interest expense debt.

+ References

No definition available.

+ Details

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- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(4))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(2))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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- 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)
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
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-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (a)
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-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ 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
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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- 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

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Balance Type:	na
Period Type:	duration

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
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-Subparagraph (SX 210.5-02.22(a)(2))
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-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

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Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of principal amount of debt redeemed.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
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- Definition

Amount, after accumulated amortization, of debt discount.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
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-Paragraph 1A
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 50
-Section 40
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-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585

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Balance Type:	credit
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- Definition

The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3291-108585

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	dei_LegalEntityAxis=agen_AntigenicsLimitedLiabilityCompanyMember
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- Details

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- Details

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- Details

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- Details

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- Details

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Debt (Narrative) (Details) - USD ($)				1 Months Ended		12 Months Ended
Debt (Narrative) (Details) - USD ($)	Feb. 18, 2020	Feb. 17, 2020	Feb. 28, 2017	Jan. 31, 2018	Mar. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Feb. 20, 2015
Debt Instrument [Line Items]
Remaining debt payment							$ 161,847,000
Debt discount						$ 120,000	788,000
Loss on extinguishment of debt							10,767,000
Long-term Debt, Gross						$ 14,146,000	14,146,000
Antigenics LLC [Member]
Debt Instrument [Line Items]
Debt instrument redemption price percentage						17.50%
Subsequent Event [Member]
Debt Instrument [Line Items]
Warrants issued	675,000
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 4.48
Notes 2015 [Member]
Debt Instrument [Line Items]
Debt discount					$ 700,000
Debt discount amortization period					3 years
2013 Warrants [Member]
Debt Instrument [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights						$ 4.41			$ 5.10
Warrant expiration date			Apr. 15, 2017		Apr. 15, 2019
2013 Warrants [Member] \| Common Stock [Member]
Debt Instrument [Line Items]
Warrants issued						500,000			1,400,000
2013 Warrants [Member] \| Common Stock [Member] \| Subsequent Event [Member]
Debt Instrument [Line Items]
Warrants issued	1,400,000
Limited Recourse Notes [Member] \| Oberland Capital SA Zermatt LLC [Member] \| Antigenics LLC [Member]
Debt Instrument [Line Items]
Debt instrument accrued interest rate percentage						13.50%
Debt instrument period for computation of interest rate						360 days
Aquila Debentures [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage						7.00%
Long-term Debt, Gross						$ 146,000
Senior Subordinated Notes [Member] \| Notes 2013 Exchanged To Notes 2015 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount									$ 5,000,000
Senior Subordinated Notes [Member] \| Notes 2015 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount									$ 9,000,000
Debt instrument, interest rate, stated percentage									8.00%
Debt instrument, debt default provisions face amount									$ 13,500,000
Debt instrument, maturity date			Feb. 20, 2018		Feb. 20, 2020	Feb. 20, 2020
Senior Subordinated Notes [Member] \| Notes 2015 [Member] \| Subsequent Event [Member]
Debt Instrument [Line Items]
Debt instrument, debt default provisions face amount	$ 13,500,000
Remaining debt payment	$ 500,000
Debt instrument, maturity date	Feb. 20, 2023	Feb. 20, 2020
Note Purchase Agreement [Member]
Debt Instrument [Line Items]
Noncash interest expenses						$ 0	$ 849,000	$ 17,400,000
Note Purchase Agreement [Member] \| Oberland Capital SA Zermatt LLC [Member]
Debt Instrument [Line Items]
Remaining debt payment				$ 161,900,000
Loss on extinguishment of debt				$ 10,800,000