Goodwill and Intangible Assets, Net - Goodwill and 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]
Gross Carrying Value	$ 824.7	$ 722.4
Accumulated Amortization	(466.9)	(370.5)
Goodwill	1,139.3	885.6	$ 790.2
Completed technology
Goodwill and Intangible Assets Disclosure [Line Items]
Gross Carrying Value	489.7	402.7
Accumulated Amortization	(251.7)	(201.3)
Customer relationships
Goodwill and Intangible Assets Disclosure [Line Items]
Gross Carrying Value	316.2	301.8
Accumulated Amortization	(197.1)	(152.5)
Backlog, trade name and other
Goodwill and Intangible Assets Disclosure [Line Items]
Gross Carrying Value	18.8	17.9
Accumulated Amortization	$ (18.1)	$ (16.7)
Minimum | Completed technology
Goodwill and Intangible Assets Disclosure [Line Items]
Life (years)	2 years
Minimum | Customer relationships
Goodwill and Intangible Assets Disclosure [Line Items]
Life (years)	4 years
Minimum | Backlog, trade name and other
Goodwill and Intangible Assets Disclosure [Line Items]
Life (years)	1 year
Maximum | Completed technology
Goodwill and Intangible Assets Disclosure [Line Items]
Life (years)	15 years
Maximum | Customer relationships
Goodwill and Intangible Assets Disclosure [Line Items]
Life (years)	15 years
Maximum | Backlog, trade name and other
Goodwill and Intangible Assets Disclosure [Line Items]
Life (years)	5 years