Fair Value Measurements - Schedule of Contingent Consideration Liabilities Measured at Fair Value (Detail) - Contingent Consideration [Member] - Significant Unobservable Inputs (Level 3) [Member] - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 3,009	$ 3,200	$ 14,466
Fair value adjustments	57		(454)
Settlements		$ (3,200)	(10,979)
Interest accretion	47		206
Foreign currency translation loss (gain)			(126)
Ending balance	$ 3,113		$ 3,113