Collaborations - Summary of Changes in Balances of Company's Related Party Collaboration Receivables and Contract Liabilities (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2022
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Related party collaboration receivables, Beginning balance		$ 110
Ultragenyx [Member] | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Deferred revenue, Beginning balance	$ 6,170	8,080
Deferred revenue, Deductions	(6,170)	(8,080)
Deferred revenue, Ending balance	0	0
Related party collaboration receivables, Beginning balance	14	110
Related party collaboration receivables, Additions		14
Related party collaboration receivables, Deductions	(14)	(124)
Related party collaboration receivables, Ending balance	$ 0	$ 0