Leases - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Dec. 31, 2024	Sep. 30, 2026
Lessee, Lease, Description [Line Items]
Remaining lease team		4 months 24 days
Discount rate		10.50%
Pennsylvania \| Building
Lessee, Lease, Description [Line Items]
Annual base rent		$ 0.2
Operating lease, expense		$ 0.1
Annual rent increase (as a percent)		2.40%
Lease term		5 years 3 months
Maryland \| Building
Lessee, Lease, Description [Line Items]
Annual rent increase (as a percent)		2.50%
Termination fee	$ 0.3
Decrease in lease liability		$ 0.3
Decrease in right of use asset		0.3
Annual base rent		$ 0.2

Increase (Decrease) in Right Of Use Asset

No definition available.

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Balance Type:	credit
Period Type:	duration

- Definition

Lessee, Operating Lease, Annual Base Rent

+ References

No definition available.

+ Details

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

- Definition

Lessee, Operating Lease, Liability, Annual Base Rent

+ References

No definition available.

+ Details

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

- Definition

Lessee Operating Lease Remaining Lease Team

+ References

No definition available.

+ Details

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Data Type:	xbrli:durationItemType
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- Definition

Lessee, Operating Lease, Termination Fee

+ References

No definition available.

+ Details

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Namespace Prefix:	avtx_
Data Type:	xbrli:monetaryItemType
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Period Type:	duration

- Definition

Operating Leases, Rent Expense, Annual Increase, Percent

+ References

No definition available.

+ Details

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Namespace Prefix:	avtx_
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- Definition

Amount of increase (decrease) in obligation for operating lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-28

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (g)(1)
-SubTopic 20
-Topic 842
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-4

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Balance Type:	debit
Period Type:	duration

- 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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 7A
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-7A

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-3

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Discount rate used by lessee to determine present value of operating lease payments.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-3

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Term of lessee's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-3

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	na
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- Definition

Amount of operating lease expense. Excludes sublease income.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 4
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479041/842-20-45-4

+ Details

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Period Type:	duration

- Details

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- Details

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