Other Current and Non-Current Liabilities - Schedule of Other Current Liabilities (Detail) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Other Liabilities Current [Abstract]
Contingent consideration payable	$ 253.7	$ 323.6
Accrued payables from acquisitions	137.5
Accrued accounts payable	64.2	58.1
Accrued compensation liability	48.8	61.7
Value-added taxes payable	6.8	6.4
Other current liabilities	41.2	12.6
Total other current liabilities	$ 552.2	$ 462.4