Collaboration and License Agreements and Supply Agreements - Summary of Recognized Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	$ 16,924	$ 25,147	$ 40,010	$ 59,140
Collaboration and License Agreements and Supply Agreements
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	16,924	25,147	40,010	59,140
Collaboration and License Agreements and Supply Agreements \| Bristol-Myers Squibb Company ("BMS")
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	189	4,343	5,591	8,774
Collaboration and License Agreements and Supply Agreements \| Merck Sharp & Dohme Corporation ("Merck")
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	83	10,157	2,776	11,367
Collaboration and License Agreements and Supply Agreements \| Merck KGaA, Darmstadt, Germany (operating in the United States and Canada under the name ''EMD Serono'')
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue		166	8	2,200
Collaboration and License Agreements and Supply Agreements \| Astellas Pharma Inc. ("Astellas")
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	9,988	4,985	23,593	4,985
Collaboration and License Agreements and Supply Agreements \| Tasly Biopharmaceuticals Co., Ltd. ("Tasly")
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	5,072		5,072	25,000
Collaboration and License Agreements and Supply Agreements \| Vaxcyte
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	1,592	1,496	2,970	2,814
Collaboration and License Agreements and Supply Agreements \| BioNova Pharmaceuticals, Ltd. ("BioNova")
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue		4,000		4,000
BMS Agreement and the 2018 BMS Master Services Agreement
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Revenues	189	4,343	5,591	8,774
BMS Agreement and the 2018 BMS Master Services Agreement \| Research and Development Services
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Revenues		107	413	591
BMS Agreement and the 2018 BMS Master Services Agreement \| Materials Supply
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Revenues	189	4,236	5,178	8,183
2020 Merck Master Services Agreement
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	83	10,157	2,776	11,367
2020 Merck Master Services Agreement \| Ongoing Performance Related to Unsatisfied Performance Obligations
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue				862
2020 Merck Master Services Agreement \| Contingent Payment
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue		10,000		10,000
2020 Merck Master Services Agreement \| Research and Development Services
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	20	136	224	402
2020 Merck Master Services Agreement \| Materials Supply
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	63	21	2,552	103
2019 EMD Serono Supply Agreement
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue		166	8	2,200
2019 EMD Serono Supply Agreement \| Research and Development Services
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue		78	6	494
2019 EMD Serono Supply Agreement \| Materials Supply
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue		88	2	1,706
Supply Agreement \| Vaxcyte
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	1,592	1,496	2,970	2,814
Supply Agreement \| Vaxcyte \| Research and Development Services
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	636	651	1,707	1,794
Supply Agreement \| Vaxcyte \| Materials Supply
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	956	845	1,263	1,020
Astellas License and Collaboration Agreement
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	9,988	4,985	23,593	4,985
Astellas License and Collaboration Agreement \| Ongoing Performance Related to Unsatisfied Performance Obligations
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	5,612	1,925	11,423	1,925
Astellas License and Collaboration Agreement \| Research and Development Services
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	1,920	809	4,639	809
Astellas License and Collaboration Agreement \| Financing Component on Unearned Revenue
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	2,456	$ 2,251	7,531	2,251
Tasly License Agreement
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	5,072		5,072	25,000
Tasly License Agreement \| Upfront Payment
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue				$ 25,000
Tasly License Agreement \| Contingent Payment
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	5,000		5,000
Tasly License Agreement \| Research and Development Services
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Total revenue	$ 72		$ 72