Property, Plant and Equipment (Narrative) (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]
Property, plant and equipment, gross	$ 1,679.4	$ 1,842.0
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	797.9	875.2
Depreciation	$ 27.5	$ 113.8	$ 113.3	$ 90.8