License and Collaboration Agreements - Summary of Revenues by Collaboration and by Category of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
License And Collaboration Agreements [Line Items]
Collaboration and license revenue	$ 9,461	$ 1,750
Gilead Access Rights
License And Collaboration Agreements [Line Items]
Collaboration and license revenue	7,711
Taiho Collaboration Agreement
License And Collaboration Agreements [Line Items]
Collaboration and license revenue	$ 1,750	$ 1,750