Balance Sheet Components - Schedule of Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Balance Sheet Related Disclosures [Abstract]
Prepaid research and development	$ 5,182	$ 5,218
Prepaid clinical trial	2,284	3,298
Deferred offering costs	722	545
Prepaid insurance	74	148
Prepaid bonus	54	427
Other	380	863
Total prepaid expenses and other current assets	$ 8,696	$ 10,499

Prepaid bonus.

No definition available.

Name:	tsha_PrepaidBonus
Namespace Prefix:	tsha_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Prepaid clinical trial.

+ References

No definition available.

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

Prepaid research and development contracts.

+ References

No definition available.

+ Details

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Namespace Prefix:	tsha_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

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- Definition

Specific incremental costs directly attributable to a proposed or actual offering of securities which are deferred at the end of the reporting period.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 340
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 5.A)
-URI https://asc.fasb.org/extlink&oid=122040515&loc=d3e105025-122735

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

Amount of current assets classified as other.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(8))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 852
-SubTopic 10
-Section 55
-Paragraph 10
-URI https://asc.fasb.org/extlink&oid=84165509&loc=d3e56426-112766

+ Details

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Period Type:	instant

- Definition

Amount of asset related to consideration paid in advance for costs that provide economic benefits in future periods, and amount of other assets that are expected to be realized or consumed within one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(9))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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Balance Type:	debit
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- Definition

Amount of asset related to consideration paid in advance for insurance that provides economic benefits within a future period of one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 340
-SubTopic 10
-Section 45
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=6387103&loc=d3e6435-108320

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (g)(1)
-URI https://asc.fasb.org/extlink&oid=124098289&loc=d3e6676-107765

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 340
-SubTopic 10
-Section 05
-Paragraph 5
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126905020&loc=d3e5879-108316

+ Details

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