Goodwill and Intangible Assets (Schedule Of Intangible Assets Subject To Amortization) (Details) - USD ($) $ in Millions	6 Months Ended
	Mar. 27, 2020	Sep. 27, 2019
Finite-Lived Intangible Assets [Line Items]
Document Period End Date	Mar. 27, 2020
Accumulated Amortization	$ (89.8)	$ (74.5)
Total intangible assets, Gross Carrying Amount	175.2	182.4
Total intangible assets, Net Carrying Amount	$ 85.4	107.9
Customer relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period (Years)	5 years
Finite-Lived Intangible Assets, Gross	$ 18.2	25.6
Accumulated Amortization	(13.9)	(19.5)
Net Carrying Amount	$ 4.3	6.1
Technology-Based Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period (Years)	4 years 1 month 6 days
Finite-Lived Intangible Assets, Gross	$ 94.4	94.4
Accumulated Amortization	(65.0)	(48.9)
Net Carrying Amount	$ 29.4	45.5
Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period (Years)	3 years
Finite-Lived Intangible Assets, Gross	$ 1.6	1.6
Accumulated Amortization	(1.6)	(1.3)
Net Carrying Amount	0.0	0.3
Computer Software, Intangible Asset [Member]
Finite-Lived Intangible Assets [Line Items]
Accrued Liabilities	$ 14.2	20.1
Weighted Average Amortization Period (Years)	3 years 1 month 6 days
Finite-Lived Intangible Assets, Gross	$ 25.1	24.9
Accumulated Amortization	(9.3)	(4.8)
Net Carrying Amount	$ 15.8	20.1
In Process Research and Development [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period (Years)	0 years
Finite-Lived Intangible Assets, Gross	$ 35.9	35.9
Accumulated Amortization	0.0	0.0
Net Carrying Amount	$ 35.9	$ 35.9