Collaboration, License, and Other Agreements - Sanofi, Immuno-Oncology Narrative (Details) - Sanofi Collaboration Agreement, Immuno-oncology - USD ($)		1 Months Ended		3 Months Ended	12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Aug. 31, 2018	Dec. 31, 2018	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2015
Disaggregation of Revenue [Line Items]
Remaining performance obligation					$ 570,300,000
Libtayo
Disaggregation of Revenue [Line Items]
Upfront payment made			$ 20,000,000
Libtayo | Through December 31, 2023
Disaggregation of Revenue [Line Items]
Percentage of royalties to be paid			8.00%
Libtayo | January 1, 2024 Through December 31, 2026
Disaggregation of Revenue [Line Items]
Percentage of royalties to be paid			2.50%
IO Discovery Agreement
Disaggregation of Revenue [Line Items]
Up-front payment received							$ 265,000,000
Percentage of quarterly profits require to be paid for reimbursement of development costs					10.00%
Contingent reimbursement obligation					$ 103,000,000
BCMAxCD3 Program
Disaggregation of Revenue [Line Items]
Aggregate payment received with regards to amendment				$ 461,900,000
Expenditure costs cap	$ 70,000,000
MUC16xCD3 Program
Disaggregation of Revenue [Line Items]
Expenditure costs cap	$ 50,000,000
IO License and Collaboration Agreement
Disaggregation of Revenue [Line Items]
Up-front payment received							375,000,000
IO License and Collaboration Agreement | PD-1
Disaggregation of Revenue [Line Items]
Maximum amount of sales milestone payments if total sales achieve specific levels					375,000,000
Levels of twelve month sales at which sales milestone payments would be received		$ 2,000,000,000
Period for achieving sales target for milestone payment, rolling basis		12 months
IO Agreement
Disaggregation of Revenue [Line Items]
Up-front payment received							$ 640,000,000
Amended IO Discovery Agreement | Other operating income
Disaggregation of Revenue [Line Items]
Cumulative catch-up adjustment to revenue, modification of contract					$ 66,900,000	$ 135,400,000