Goodwill and Intangible Assets, Net - Amortization of Intangible Assets (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 27, 2015	Sep. 28, 2014	Sep. 29, 2013
Goodwill and Intangible Assets Disclosure [Line Items]
Amortization of intangible assets	$ 96.5	$ 92.8	$ 84.8
Completed technology
Goodwill and Intangible Assets Disclosure [Line Items]
Amortization of intangible assets	50.4	43.9	39.0
Customer relationships
Goodwill and Intangible Assets Disclosure [Line Items]
Amortization of intangible assets	44.6	45.0	42.6
Backlog, trade name and other
Goodwill and Intangible Assets Disclosure [Line Items]
Amortization of intangible assets	$ 1.5	$ 3.9	$ 3.2