Segment Information (Geographic Revenue) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Sep. 27, 2019	Jun. 28, 2019	Mar. 29, 2019	Dec. 28, 2018	Sep. 28, 2018	Jun. 29, 2018	Mar. 30, 2018	Dec. 29, 2017	Sep. 27, 2019	Sep. 28, 2018	Sep. 29, 2017
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 827.4	$ 767.0	$ 810.4	$ 972.0	$ 1,008.4	$ 894.3	$ 913.4	$ 1,051.9	$ 3,376.8	$ 3,868.0	$ 3,651.4
Total Americas [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									1,860.4	1,946.2	1,615.4
China
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									718.7	982.8	1,018.8
Taiwan
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									271.1	339.1	335.4
South Korea
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									365.5	432.7	531.8
Asia
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									134.9	144.6	117.4
Europe, Middle East and Africa [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax									$ 26.2	$ 22.6	$ 32.6