Research and Collaboration Arrangements - Roche Agreement - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended
	Nov. 30, 2017	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenues		$ 1,219,000	$ 2,000,000
Roche | 2017 Roche Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Non-refundable upfront payments received	$ 21,000,000.0
Contingent payment for each nominated product beyond the first three	1,000,000.0
Maximum contingent payment upon exercise of the option to convert a product	30,000,000.0
Maximum development milestone payments	223,000,000.0
Development milestone payments relating to Choroideremia	86,000,000.0
Maximum sales-based milestone payments	$ 123,000,000.0
Non-refundable development milestone payments		10,000,000.0
Revenues		0.0	$ 1,600,000
Deferred revenue		0		$ 0
Accounts receivable		0		0
Aggregate amount of transaction price allocated to remaining performance obligation		$ 0.0		$ 0.0