Commitments and Contingencies - Additional Information (Detail) $ in Millions	1 Months Ended				3 Months Ended	12 Months Ended
	Nov. 30, 2022 USD ($)	Oct. 31, 2021 USD ($)	Mar. 31, 2021 USD ($)	Oct. 31, 2018 Suite	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 Suite	Jun. 30, 2018 Suite	Jun. 30, 2018 mo
Commitments And Contingencies [Line Items]
Amendment Implemented Fee					$ 60.0
Long-Term Purchase Commitment, Amount					$ 54.7
Research and Development Expense [Member]
Commitments And Contingencies [Line Items]
Non Refundable Advance Payments						$ 2.6
First Installments [Member]
Commitments And Contingencies [Line Items]
Installments Date of implemented fee					Mar. 01, 2024
Amendment Implemented Fee					$ 20.0
Thermo Fisher Scientific, Inc. [Member]
Commitments And Contingencies [Line Items]
Research and development expense						0.0	$ 54.0	$ 0.0
CRO [Member]
Commitments And Contingencies [Line Items]
Cancellable future commitments						580.0
CRO [Member] | Other Funding Commitments [Member]
Commitments And Contingencies [Line Items]
Expenditures incurred by CROs						$ 112.2	$ 78.7	$ 47.9
Supply Agreement [Member] | Thermo Fisher Scientific, Inc. [Member]
Commitments And Contingencies [Line Items]
Number of dedicated clean room suites										4	4
Agreement expiration date				Dec. 31, 2028
Supply Agreement [Member] | Thermo Fisher Scientific, Inc. [Member] | Research and Development Expense [Member]
Commitments And Contingencies [Line Items]
Research and development expense		$ 24.4
Derecognition of right of use asset		23.4
Derecognition of lease liabilities		20.1
Recognition of loss		3.3
Non Refundable Advance Payments		$ 21.1
Catalent Agreements [Member]
Commitments And Contingencies [Line Items]
Recognition Of Right Of Use Asset	$ 19.2
Increase in long-term deposits manufacturing	$ 3.9
Catalent Agreements [Member] | Research and Development Expense [Member]
Commitments And Contingencies [Line Items]
Derecognition of right of use asset			$ 22.8
Derecognition of lease liabilities			20.0
Recognition of loss			$ 2.8
Catalent Agreements [Member] | Paragon [Member]
Commitments And Contingencies [Line Items]
Number of dedicated clean room suites | Suite				2					4
Number of additional clean room suites available on optional reserve | Suite				2
Agreement expiration date				Dec. 31, 2024
Clinical and Commercial Supply Agreement [Member] | Aldevron LLC [Member]
Commitments And Contingencies [Line Items]
Agreement expiration date						Dec. 31, 2026
Agreement expiration description						The Company has the option to extend the term of the Aldevron Agreements by one year if the Company delivers a written notice of its intention to extend to Aldevron no later than June 1, 2025. Both parties have the right to early terminate without additional penalty. The Company has determined that the Aldevron Agreements do not contain an embedded lease because it does not convey the right to control the use of Aldevron’s facility or related equipment therein.