Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Sep. 30, 2019	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Loss Contingencies [Line Items]
Research agreement, payable amount		$ 4,420		$ 4,420		$ 2,805
Research and development		40,477	$ 29,002	$ 81,617	$ 50,442
Research agreement, expiration period				2022-12
Research agreement, payment				$ 2,400	1,200
Amended Sanofi Agreement [Member] | Sanofi Pasteur Inc [Member]
Loss Contingencies [Line Items]
Upfront payment received		2,500		$ 2,500
Roche Diagnostics Corporation Master Supply Agreement [Member]
Loss Contingencies [Line Items]
Agreement extended date				Dec. 31, 2024
Commitment amount				$ 10,500
Purchase commitments, year 2022		3,500		3,500
Purchase commitments, year 2023		3,500		3,500
Purchase commitments, year 2024		3,500		3,500
Research and development		1,300	1,300	5,700	2,600
MIT Research Agreement [Member]
Loss Contingencies [Line Items]
Research agreement, payable amount		0		0
Research and development		300	$ 300	700	$ 700
Research agreement, committed amount	$ 4,100
Research agreement, expiration period	2022-12
MIT Exclusive Patent License Agreement [Member]
Loss Contingencies [Line Items]
Payment of milestones		700		700
MIT Exclusive Patent License Agreement [Member] | Sanofi Pasteur Inc [Member]
Loss Contingencies [Line Items]
Upfront payment received		3,400		3,400
MIT Exclusive Patent License Agreement [Member] | Milestone Payment One [Member]
Loss Contingencies [Line Items]
License agreement, milestone payments				1,375
MIT Exclusive Patent License Agreement [Member] | Milestone Payment Two [Member]
Loss Contingencies [Line Items]
License agreement, milestone payments				1,250
MIT Exclusive Patent License Agreement [Member] | Milestone payment Three [Member]
Loss Contingencies [Line Items]
Upfront payment received		$ 900		$ 900