Earnings Per Share (Calculation of Net Earnings Per Common Share ("EPS") - Basic and Diluted) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2018	Jul. 01, 2018	Apr. 01, 2018	Dec. 31, 2017	Oct. 01, 2017	Jul. 02, 2017	Apr. 02, 2017	Jan. 01, 2017	Sep. 30, 2018	Oct. 01, 2017	Oct. 02, 2016
Earnings Per Share [Abstract]
Net earnings attributable to Starbucks	$ 755.8	$ 852.5	$ 660.1	$ 2,250.2	$ 788.5	$ 691.6	$ 652.8	$ 751.8	$ 4,518.3	$ 2,884.7	$ 2,817.7
Weighted average common shares and common stock units outstanding (for basic calculation)									1,382.7	1,449.5	1,471.6
Dilutive effect of outstanding common stock options and RSUs									11.9	12.0	15.1
Weighted average common and common equivalent shares outstanding (for diluted calculation)									1,394.6	1,461.5	1,486.7
Earnings Per Share, Basic									$ 3.27	$ 1.99	$ 1.91
Earnings Per Share, Diluted	$ 0.56	$ 0.61	$ 0.47	$ 1.57	$ 0.54	$ 0.47	$ 0.45	$ 0.51	$ 3.24	$ 1.97	$ 1.90