Fair Value Measurements - Summary of Reconciliation of Recurring Fair Value Measurements (Detail) - Deferred Consideration Obligation [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 173,024	$ 161,540
Net realized losses	3,760	3,098
Net unrealized losses/(gains)	2,208	(4,404)
Settlements	(3,692)	(3,087)
Ending balance	$ 175,300	$ 157,147