Business Acquisitions (Narrative) (Details) - USD ($)	Dec. 23, 2015	Feb. 12, 2014
4-antibody acquisition [Member]
Business Acquisition [Line Items]
Issuance of stock for acquisition, share		3,334,079
Issuance of stock for acquisition, value		$ 10,100,000
Contingent Consideration		40,000,000
Business Combination, Contingent Consideration, Liability		9,700,000
PhosImmune Inc. [Member]
Business Acquisition [Line Items]
Issuance of stock for acquisition, share	1,631,521
Issuance of stock for acquisition, value	$ 7,400,000
Contingent Consideration	35,000,000
Business Combination, Contingent Consideration, Liability	2,500,000
Amount Received by Stock Holders Cash	2,500,000
Contingent Milestone 1 [Member] \| 4-antibody acquisition [Member]
Business Acquisition [Line Items]
Contingent Consideration		20,000,000
Market Capitalization		$ 300,000,000
Debt Instrument, Redemption, Threshold Trading Days		10 days
Contingent Milestone 1 [Member] \| PhosImmune Inc. [Member]
Business Acquisition [Line Items]
Contingent Consideration	$ 5,000,000
Debt Instrument, Redemption, Threshold Trading Days	60 days
Trading Price of our Common Stock	$ 8.00
Contingent Milestone 2 [Member] \| 4-antibody acquisition [Member]
Business Acquisition [Line Items]
Contingent Consideration		$ 10,000,000
Market Capitalization		$ 750,000,000
Debt Instrument, Redemption, Threshold Trading Days		30 days
Contingent Milestone 2 [Member] \| PhosImmune Inc. [Member]
Business Acquisition [Line Items]
Contingent Consideration	$ 15,000,000
Debt Instrument, Redemption, Threshold Trading Days	60 days
Trading Price of our Common Stock	$ 13.00
Contingent Milestone 3 [Member] \| 4-antibody acquisition [Member]
Business Acquisition [Line Items]
Contingent Consideration		$ 10,000,000
Market Capitalization		$ 1,000,000,000
Debt Instrument, Redemption, Threshold Trading Days		30 days
Contingent Milestone 3 [Member] \| PhosImmune Inc. [Member]
Business Acquisition [Line Items]
Contingent Consideration	$ 15,000,000
Debt Instrument, Redemption, Threshold Trading Days	60 days
Trading Price of our Common Stock	$ 19.00

Common stock trading price per share.

No definition available.

Name:	agen_CommonStockTradingPricePerShare
Namespace Prefix:	agen_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt instrument redemption threshold trading period.

+ References

No definition available.

+ Details

Name:	agen_DebtInstrumentRedemptionThresholdTradingPeriod
Namespace Prefix:	agen_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Minimum Market Capitalization threshold that must be exceeded to exercise right to repay outstanding balance with common stock at maturity.

+ References

No definition available.

+ Details

Name:	agen_DebtInstrumentRepaymentTermMinimumMarketCapitalizationAmountRequiredForEquityConversionAtDebtMaturity
Namespace Prefix:	agen_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- 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_BusinessAcquisitionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

For contingent consideration arrangements recognized in connection with a business combination, this element represents an estimate of the high-end of the potential range (undiscounted) of the consideration which may be paid.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (c)(3)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

+ Details

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

- Definition

Amount of liability recognized arising from contingent consideration in a business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 35
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=116859824&loc=d3e6819-128478

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 25
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6911189&loc=d3e6408-128476

+ Details

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

- Definition

The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

+ References

+ Details

Name:	us-gaap_PaymentsToAcquireBusinessesGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Number of shares of stock issued during the period pursuant to acquisitions.

+ 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(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

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(28))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_StockIssuedDuringPeriodSharesAcquisitions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Value of stock issued pursuant to acquisitions during the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

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 210.5-02.29-31)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_StockIssuedDuringPeriodValueAcquisitions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_BusinessAcquisitionAxis=agen_A4antibodyAcquisitionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=agen_PhosImmuneIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ContingentConsiderationByTypeAxis=agen_ContingentMilestone1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ContingentConsiderationByTypeAxis=agen_ContingentMilestone2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ContingentConsiderationByTypeAxis=agen_ContingentMilestone3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: