Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Accrued payroll and related costs	$ 465.8	$ 344.4
Accrued clinical expenses	283.0	142.7
Accrued sales-related charges, deductions, and royalties	423.9	249.0
Income taxes payable	19.5	49.4
Other accrued expenses and liabilities	329.6	425.9
Accrued expenses and other current liabilities	$ 1,521.8	$ 1,211.4