Astellas Agreements - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended		3 Months Ended	6 Months Ended
	Oct. 21, 2022	Oct. 31, 2022	Mar. 31, 2021	Jun. 30, 2023	Jun. 30, 2023	Dec. 31, 2022
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Common stock, shares issued				64,432,637	64,432,637	63,207,507
Probability of option exercise		50.00%
Decrease in revenue previously recognized					$ 3,100
Revenues				$ 2,395	7,101
Deferred revenue recorded within current liabilities				20,243	20,243	$ 33,557
Deferred revenue recorded within long-term liabilities				$ 6,212	6,212
TSHA-120
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment			$ 5,500
Astellas
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment	$ 20,000
Transaction price		$ 36,100			36,059
Deferred revenue		$ 36,100
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
Fair value of shares transferred, Value		$ 13,950
Share price		$ 1.92
Transaction price		$ 16,100
Difference of market value paid		$ 30,000
Astellas | TSHA-120
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment					20,000
Transaction price					36,100
Astellas | TSHA-120 | Private Placement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Transaction price					$ 16,100