Employee Stock Plans - Net Share-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jul. 03, 2015	Jun. 27, 2014	Jul. 03, 2015	Jun. 27, 2014
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total share-based compensation expense	$ 11,356	$ 11,414	$ 36,594	$ 30,054
Income tax benefit for share-based compensation	(3,455)	(3,564)	(11,371)	(9,301)
Cost of revenues - Product
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total share-based compensation expense	1,263	950	3,578	2,374
Cost of revenues - Service
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total share-based compensation expense	1,066	1,330	3,004	3,392
Research and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total share-based compensation expense	1,717	1,771	5,109	4,392
Selling, general and administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total share-based compensation expense	$ 7,310	$ 7,363	$ 24,903	$ 19,896