Condensed Consolidated Statements of Stockholders' (Deficit) Equity (Parenthetical) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Underwritten Public Offering
Underwriting discounts and commissions and other offering costs	$ 44	$ 6	$ 14,323	$ 14,329

Underwriting discounts and commissions and other offering costs.

No definition available.

Name:	tsha_UnderwritingDiscountsAndCommissionsAndOtherOfferingCosts
Namespace Prefix:	tsha_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration