Revenue - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended
	Feb. 28, 2019	Mar. 31, 2022	Mar. 31, 2021
Disaggregation Of Revenue [Line Items]
Revenue from collaboration agreement		$ 38,620,000	$ 38,442,000
Medicare Reimbursements
Disaggregation Of Revenue [Line Items]
Revenue from collaboration agreement		1,400,000	800,000
Medicare Reimbursements | Immune Medicine Service Revenue
Disaggregation Of Revenue [Line Items]
Revenue from collaboration agreement		200,000
Medicare Reimbursements | MRD Service Revenue
Disaggregation Of Revenue [Line Items]
Revenue from collaboration agreement		1,200,000
M R D Development Agreements | Maximum
Disaggregation Of Revenue [Line Items]
Additional milestone payment receivable		330,500,000
Genentech Collaboration Agreement
Disaggregation Of Revenue [Line Items]
Revenue from collaboration agreement		12,300,000	$ 15,600,000
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
Genentech Collaboration Agreement | Maximum | Development Milestones
Disaggregation Of Revenue [Line Items]
Expected revenue through milestone payments		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
Genentech Collaboration Agreement | Minimum
Disaggregation Of Revenue [Line Items]
Expected revenue through milestone payments		$ 1,800,000
Revenue recognition expected period		7 years