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, 2018	Jun. 30, 2019	Jun. 30, 2018
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 3,009	$ 13,345	$ 14,466	$ 14,864
Fair value adjustments	57	21	(454)	(1,278)
Settlements			(10,979)	(925)
Interest accretion	47	85	206	272
Foreign currency translation loss (gain)		(592)	(126)	(74)
Ending balance	$ 3,113	$ 12,859	$ 3,113	$ 12,859