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, 2016	Dec. 31, 2015
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 14,517
Additions		$ 9,064
Interest accretion	437	109
Foreign currency translation (gain) loss	(663)	135
Ending balance	$ 14,291	$ 9,308