Collaboration and License Agreements - License Agreements - Additional Information (Detail) - USD ($)	3 Months Ended			6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Licensing Agreement [Line Items]
Research and development expense	$ 53,800,000	$ 41,128,000	$ 33,005,000	$ 94,928,000	$ 60,379,000
Infectious Disease Research Institute
Licensing Agreement [Line Items]
Milestone payment amount				0
Infectious Disease Research Institute | Research and Development
Licensing Agreement [Line Items]
Non-refundable upfront cash payments				2,000,000.0
Infectious Disease Research Institute | Sponsored Research Agreement
Licensing Agreement [Line Items]
Research and development expense				200,000
Infectious Disease Research Institute | Sponsored Research Agreement | Minimum
Licensing Agreement [Line Items]
Minimum annual payments in support of research activities through May 2024				2,000,000
iosBio Ltd. Exclusive License Agreement
Licensing Agreement [Line Items]
Accrued reimbursable costs payable	$ 200,000			$ 200,000		$ 500,000