Fair Value Measurements - Summary of Reconciliation of Recurring Fair Value Measurements (Detail) - Deferred Consideration Obligation [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 230,137	$ 173,024
Net realized losses	4,270	3,760
Net unrealized losses	(2,832)	2,208
Settlements	(4,429)	(3,692)
Ending balance	$ 227,146	$ 175,300