Other Current and Non-Current Liabilities - Schedule of Other Non-Current Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Other Liabilities Noncurrent [Abstract]
Contingent consideration obligation	$ 171,200	$ 140,100
Accrued payables from acquisitions	120,000
Deferred consideration payable from acquisitions	24,100
Uncertain tax positions, including interest and penalties	25,640	15,851
Other non-current liabilities	2,116	2,462
Total other non-current liabilities	$ 343,056	$ 158,413