Collaboration, License, and Other Agreements - Schedule of Accounts Receivable and Deferred Revenue Information, Antibody Collaboration (Details) - Sanofi Collaboration Agreement, Antibody - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Accounts receivable	$ 407.7	$ 272.7
Deferred revenue	$ 347.7	$ 328.8