Astellas Agreements - Additional Information (Details) - USD ($)		1 Months Ended		3 Months Ended
	Oct. 21, 2022	Oct. 31, 2022	Mar. 31, 2021	Mar. 31, 2023	Dec. 31, 2022
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Common stock, shares issued				63,473,349	63,207,507
Probability of option exercise		50.00%
Deferred revenue				$ 28,900,000
Revenues				4,706,000
TSHA-120
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment			$ 5,500,000
Astellas
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment	$ 20,000,000.0	$ 20,000,000.0
Transaction price		36,100,000		36,059
Deferred revenue		$ 36,100,000
Astellas | Securities Purchase Agreement | Private Placement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Common stock, shares issued	7,266,342	7,266,342
Aggregate gross proceeds	$ 30,000,000.0
Fair value of shares transferred, Value		$ 13,950,000
Share price		$ 1.92
Transaction price		$ 16,100,000
Difference of market value paid		$ 30,000,000.0
Astellas | TSHA-120
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment				20,000,000.0
Transaction price				36,100,000
Astellas | TSHA-120 | Private Placement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Transaction price				$ 16,100,000