Supplemental Balance Sheet Information (Property, Plant And Equipment, net) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Sep. 30, 2018
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 13,667.2	$ 13,197.1
Accumulated depreciation	(7,531.7)	(7,268.0)
Property, plant and equipment, net	6,135.5	5,929.1
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	46.8	46.8
Buildings [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	617.4	557.3
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	7,608.2	7,372.8
Store Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	2,511.3	2,400.2
Roasting Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	689.9	658.8
Furniture, Fixtures and Other [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,710.8	1,659.3
Work in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 482.8	$ 501.9