Base lease rent period.

No definition available.

Name:	arvn_BaseLeaseRentPeriod
Namespace Prefix:	arvn_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt instrument loan forgiveness.

+ References

No definition available.

+ Details

Name:	arvn_DebtInstrumentLoanForgiveness
Namespace Prefix:	arvn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Lease extended term month and year.

+ References

No definition available.

+ Details

Name:	arvn_LeaseExtendedTermMonthAndYear
Namespace Prefix:	arvn_
Data Type:	xbrli:gYearMonthItemType
Balance Type:	na
Period Type:	duration

- Definition

Tenant improvement allowance per square foot.

+ References

No definition available.

+ Details

Name:	arvn_TenantImprovementAllowancePerSquareFoot
Namespace Prefix:	arvn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Decrease for amounts of indebtedness forgiven by the holder of the debt instrument.

+ 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.(f))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

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

- Definition

Area of land subject to a ground lease.

+ References

No definition available.

+ Details

Name:	us-gaap_LandSubjectToGroundLeases
Namespace Prefix:	us-gaap_
Data Type:	num:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of lease cost recognized by lessee for lease contract.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918686-209980

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-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 55
-Paragraph 53
-URI http://asc.fasb.org/extlink&oid=121568110&loc=SL77918982-209971

+ Details

Name:	us-gaap_LeaseCost
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The carrying amount as of the date of the latest financial statement presented of securities which are owned but transferred to serve as collateral for letter of credit arrangements, and for which the transferee does not have the right by contract or custom to sell or re-pledge them to an unrelated party.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
-Subparagraph (b)(1)(i)
-URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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

- Details

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Namespace Prefix:
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Balance Type:
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- Details

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- Details

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- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=arvn_TwoThousandAndEighteenAssistanceAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Subsequent Events - Additional Information (Details) - State of Connecticut		1 Months Ended
	Apr. 30, 2021 USD ($)	May 31, 2021 USD ($) ft²	Jan. 31, 2021	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)
Subsequent Event [Line Items]
Lease extended term			2024-12
Scenario Forecast
Subsequent Event [Line Items]
Lease for laboratory and office space \| ft²		160,000
Letter of credit for collateralized by certificate of deposit		$ 3,500,000
Base rent period		10 years
Tenant improvement allowance per square foot		$ 150
Maximum [Member] \| Scenario Forecast
Subsequent Event [Line Items]
Base rent		7,200,000
Minimum \| Scenario Forecast
Subsequent Event [Line Items]
Base rent		$ 6,300,000
2018 Assistance Agreement
Subsequent Event [Line Items]
Debt instrument face amount				$ 2,000,000.0	$ 2,000,000.0
2018 Assistance Agreement \| Subsequent Event
Subsequent Event [Line Items]
Loan forgiveness	$ 1,000,000.0
2018 Assistance Agreement \| Maximum [Member]
Subsequent Event [Line Items]
Debt instrument face amount					2,000,000.0
Forgiveness of funding on achieving certain employment conditions				$ 1,000,000.0	$ 1,000,000.0