Goodwill and Intangible Assets (Schedule Of Intangible Assets Subject To Amortization) (Details) - USD ($) $ in Millions	6 Months Ended
	Mar. 30, 2018	Sep. 29, 2017
Finite-Lived Intangible Assets [Line Items]
Total intangible assets, Gross Carrying Amount	$ 248.3	$ 242.4
Total intangible assets, Accumulated Amortization	(185.6)	(174.6)
Total intangible assets, Net Carrying Amount	$ 62.7	67.8
Computer Software, Intangible Asset [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period (Years)	3 years
Gross Carrying Amount	$ 18.0	12.1
Accumulated Amortization	(3.0)	0.0
Net Carrying Amount	$ 15.0	12.1
Customer relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period (Years)	5 years
Gross Carrying Amount	$ 78.5	78.5
Accumulated Amortization	(65.7)	(63.4)
Net Carrying Amount	$ 12.8	15.1
Developed technology and other [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period (Years)	5 years
Gross Carrying Amount	$ 150.2	150.2
Accumulated Amortization	(116.4)	(110.9)
Net Carrying Amount	$ 33.8	39.3
Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period (Years)	3 years
Gross Carrying Amount	$ 1.6	1.6
Accumulated Amortization	(0.5)	(0.3)
Net Carrying Amount	$ 1.1	$ 1.3