Intangible Assets - Schedule of Intangible Assets (Detail) - USD ($) $ in Millions	Dec. 29, 2018	Sep. 29, 2018
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 5,669.3	$ 5,571.8
Accumulated Amortization	3,267.1	3,173.2
Developed technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	4,656.2	4,573.3
Accumulated Amortization	2,586.3	2,505.8
In-process research and development
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	16.9	5.5
Accumulated Amortization	0.0	0.0
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	556.0	556.5
Accumulated Amortization	435.9	428.1
Trade names
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	315.1	312.5
Accumulated Amortization	179.8	175.0
Distribution agreement
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	42.0	42.0
Accumulated Amortization	9.3	8.0
Non-competition agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	1.5	1.5
Accumulated Amortization	0.6	0.5
Business licenses
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	2.4	2.4
Accumulated Amortization	2.2	2.2
Total acquired intangible assets
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	5,590.1	5,493.7
Accumulated Amortization	3,214.1	3,119.6
Internal-use software
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	56.8	58.5
Accumulated Amortization	48.1	49.3
Capitalized software embedded in products
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	22.4	19.6
Accumulated Amortization	$ 4.9	$ 4.3