Revenue from Contracts with Customers - Summary of Collaboration and License Agreement Revenues by Collaborator (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Collaboration and license agreement revenues	$ 1,061,731	$ 213,263	$ 1,574,243	$ 626,909
License and Service [Member]
Disaggregation of Revenue [Line Items]
Collaboration and license agreement revenues	758,313	18,420	780,250	99,128
License and Service [Member] | Merck [Member]
Disaggregation of Revenue [Line Items]
Collaboration and license agreement revenues	725,000	0	725,000	0
License and Service [Member] | Takeda Collaboration and License Agreement [Member]
Disaggregation of Revenue [Line Items]
Collaboration and license agreement revenues	7,013	17,720	22,925	89,859
License and Service [Member] | Other Collaboration and License Agreement [Member]
Disaggregation of Revenue [Line Items]
Collaboration and license agreement revenues	$ 26,300	$ 700	$ 32,325	$ 9,269