Subsequent Events - Additional Information (Detail) - Silicon Valley Bank [Member] - Subsequent Event [Member]	Nov. 02, 2021 USD ($)
Prime Rate [Member]
Subsequent Event [Line Items]
Loan, interest rate	4.85%
Term Loan [Member]
Subsequent Event [Line Items]
Borrowing amount	$ 65,000,000.0
Loan maturity date	Oct. 01, 2026
Loan, interest rate	8.10%
Line of credit facility additional prepayment of premium percentage	9.00%
Term Loan [Member] \| Loan and Security Agreement [Member]
Subsequent Event [Line Items]
Borrowing amount	$ 30,000,000.0
Loan, payment term	The Term Loan Agreement provides for (i) on the Closing Date, $30.0 million aggregate principal amount of term loans available through October 31, 2023; (ii) an additional $10.0 million term loan facility available through October 31, 2023 upon the achievement of certain regulatory milestones prior to the time of draw; (iii) an additional $10.0 million term loan facility available through October 31, 2023 upon the achievement of certain regulatory and/or clinical milestones prior to the time of draw; and (iv) an additional discretionary $15.0 million term loan facility available upon the Company’s request and approval by SVB and the lenders.
Line of credit facility additional discretionary	$ 15,000,000.0
Line of credit	15,000,000.0
Term Loan [Member] \| Clinical Milestone Prior To Draw \| Loan and Security Agreement [Member]
Subsequent Event [Line Items]
Additional borrowing amount	10,000,000.0
Term Loan [Member] \| Tranche A Draw Period [Member] \| Loan and Security Agreement [Member]
Subsequent Event [Line Items]
Additional borrowing amount	$ 10,000,000.0
Term Loan Prepaid through November 2, 2022 [Member]
Subsequent Event [Line Items]
Line of credit facility prepayment of premium percentage	1.50%
Term Loan Prepaid through November 2, 2023 [Member]
Subsequent Event [Line Items]
Line of credit facility prepayment of premium percentage	1.00%

Line of credit facility additional discretionary.

No definition available.

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

- Definition

Line of credit facility additional prepayment of premium percentage.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

Line of credit facility prepayment of premium percentage.

+ References

No definition available.

+ Details

Name:	avro_LineOfCreditFacilityPrepaymentOfPremiumPercentage
Namespace Prefix:	avro_
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Period Type:	duration

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the 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
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

+ Details

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

- Definition

Date the credit facility terminates, in YYYY-MM-DD format.

+ References

+ Details

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

- Definition

Description of the frequency of the required periodic payments of interest, principal, or both, and the amount, if set, or a description of a formula upon which payment is based.

+ References

+ Details

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

- Definition

The effective interest rate during the reporting period.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityInterestRateDuringPeriod
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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

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