Goodwill and Intangible Assets, Net - Amortization of Intangible Assets (Detail) - USD ($) $ in Millions	12 Months Ended
	Oct. 01, 2017	Oct. 02, 2016	Sep. 27, 2015
Goodwill and Intangible Assets Disclosure [Line Items]
Amortization of intangible assets	$ 191.7	$ 161.2	$ 96.5
Completed technology
Goodwill and Intangible Assets Disclosure [Line Items]
Amortization of intangible assets	143.7	108.7	50.4
Customer relationships
Goodwill and Intangible Assets Disclosure [Line Items]
Amortization of intangible assets	45.7	46.5	44.6
Backlog, trade name and other
Goodwill and Intangible Assets Disclosure [Line Items]
Amortization of intangible assets	$ 2.3	$ 6.0	$ 1.5