Goodwill and Intangible Assets (Schedule of Intangible Assets Excluding Goodwill) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 28, 2018	Sep. 29, 2017
Intangible Assets Excluding Goodwill [Line Items]
Gross carrying amount	$ 187.2	$ 103.3
Accumulated amortization	(43.5)	(35.5)
Net carrying amount	$ 143.7	67.8
Customer Relationships [Member]
Intangible Assets Excluding Goodwill [Line Items]
Weighted average amortization period (years)	3 years 4 months 24 days
Gross carrying amount	$ 31.7	29.7
Accumulated amortization	(13.2)	(14.6)
Net carrying amount	$ 18.5	15.1
Developed Technology and Other [Member]
Intangible Assets Excluding Goodwill [Line Items]
Weighted average amortization period (years)	5 years 3 months 18 days
Gross carrying amount	$ 89.9	59.9
Accumulated amortization	(23.5)	(20.6)
Net carrying amount	$ 66.4	39.3
Trademarks [Member]
Intangible Assets Excluding Goodwill [Line Items]
Weighted average amortization period (years)	3 years
Gross carrying amount	$ 1.6	1.6
Accumulated amortization	(0.8)	(0.3)
Net carrying amount	$ 0.8	1.3
Computer Software, Intangible Asset [Member]
Intangible Assets Excluding Goodwill [Line Items]
Weighted average amortization period (years)	3 years
Gross carrying amount	$ 18.0	12.1
Accumulated amortization	(6.0)	0.0
Net carrying amount	12.0	12.1
In Process Research and Development [Member]
Intangible Assets Excluding Goodwill [Line Items]
Gross carrying amount	46.0	0.0
Accumulated amortization	0.0	0.0
Net carrying amount	$ 46.0	$ 0.0