Property, Plant and Equipment (Schedule of Property, Plant and Equipment) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 30, 2016	Dec. 29, 2017	Sep. 30, 2016	Sep. 25, 2015
Property, Plant and Equipment [Line Items]
Depreciation	$ 27.5	$ 113.8	$ 113.3	$ 90.8
Property, plant and equipment, gross	1,679.4	1,842.0
Less: accumulated depreciation	(797.9)	(875.2)
Property, plant and equipment, net	881.5	966.8
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	46.9	44.0
Buildings
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	291.1	355.5
Capitalized Software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	87.2	109.0
Machinery and Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,052.0	1,123.8
Construction in Progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 202.2	$ 209.7