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
	Dec. 31, 2019	Dec. 31, 2018
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 3,200	$ 14,466
Fair value adjustments		(149)
Settlements	$ (3,200)	(10,979)
Interest accretion		114
Foreign currency translation loss (gain)		(126)
Ending balance		$ 3,326