Segment and Geographic Information - Net Revenues based upon Source of Order by Geographic Area (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue	$ 560,323	$ 552,708	$ 482,848
North America
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue	209,727	199,103	174,343
Asia/Pacific
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue	247,241	231,840	198,695
United Kingdom
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue	36,611	32,160	27,078
Rest of Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue	$ 66,744	$ 89,605	$ 82,732