Fair Value Measurements (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jul. 02, 2017	Oct. 01, 2017	Oct. 02, 2016	Sep. 27, 2015
Available-for-sale Securities [Abstract]
Proceeds from sale of available-for-sale securities		$ 999.7	$ 680.7	$ 600.6
Trading Securities [Abstract]
Management Deferred Compensation Plan liability		105.9	101.5
Trading securities, change in net unrealized holding gain (loss)		10.5	3.6	(4.5)
Goodwill, Impairment Loss		87.2	0.0	0.0
Goodwill		1,539.2	1,719.6	$ 1,575.4
Other intangible assets		$ 441.4	$ 516.3
Maximum [Member]
Available-for-sale Securities [Abstract]
Long-term investments, contractual maturity period		5 years
Teavana [Member]
Trading Securities [Abstract]
Goodwill, Impairment Loss	$ 69.3
Goodwill		$ 398.3
Other intangible assets		117.2
Starbucks Coffee Switzerland [Member]
Trading Securities [Abstract]
Goodwill, Impairment Loss	$ 17.9
Goodwill		$ 37.0