Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Jun. 30, 2020	Sep. 30, 2020
Commitments And Contingencies [Line Items]
Contingent payments upon achievement of certain development and regulatory activities and commercial sales and licensing milestones		$ 622.4
Contingent liabilities		54.1
Clinical and Post Marketing Services
Commitments And Contingencies [Line Items]
Purchase commitments and other minimum contractual obligations		150.3
Third Party
Commitments And Contingencies [Line Items]
Contingent payments upon achievement of certain development and regulatory activities and commercial sales and licensing milestones		70.3
Early Stage Development Program | Third Party
Commitments And Contingencies [Line Items]
Contingent payments upon achievement of certain development and regulatory activities and commercial sales and licensing milestones	$ 235.0
Programs No Longer Being Developed | Third Party
Commitments And Contingencies [Line Items]
Contingent payments upon achievement of certain development and regulatory activities and commercial sales and licensing milestones		$ 236.0