Revenue - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Feb. 28, 2019	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Disaggregation Of Revenue [Line Items]
Revenue from collaboration agreement		$ 47,830,000	$ 39,467,000	$ 130,110,000	$ 116,414,000
Medicare Reimbursements
Disaggregation Of Revenue [Line Items]
Revenue from collaboration agreement		1,100,000	1,500,000	3,700,000	5,400,000
M R D Development Agreements | Maximum
Disaggregation Of Revenue [Line Items]
Additional milestone payment receivable		370,500,000		370,500,000
Genentech Collaboration Agreement
Disaggregation Of Revenue [Line Items]
Revenue from collaboration agreement		20,400,000	$ 15,000,000.0	46,500,000	$ 47,800,000
Non-refundable upfront payments received	$ 300,000,000.0			$ 300,000,000.0
Genentech Collaboration Agreement | Maximum
Disaggregation Of Revenue [Line Items]
Revenue recognition expected period				8 years
Genentech Collaboration Agreement | Maximum | Regulatory Milestones
Disaggregation Of Revenue [Line Items]
Expected revenue through milestone payments		75,000,000.0		$ 75,000,000.0
Genentech Collaboration Agreement | Maximum | Development Milestones
Disaggregation Of Revenue [Line Items]
Expected revenue through milestone payments		300,000,000.0		300,000,000.0
Genentech Collaboration Agreement | Maximum | Commercial Milestones
Disaggregation Of Revenue [Line Items]
Expected revenue through milestone payments		1,430,000,000.0		1,430,000,000.0
Genentech Collaboration Agreement | Minimum
Disaggregation Of Revenue [Line Items]
Expected revenue through milestone payments		$ 1,800,000,000		$ 1,800,000,000
Revenue recognition expected period				7 years