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		6 Months Ended
	Mar. 29, 2020	Mar. 31, 2019	Mar. 29, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Net earnings attributable to Starbucks	$ 328.4	$ 663.2	$ 1,214.1	$ 1,423.6
Weighted average common shares outstanding (for basic calculation)	1,171.8	1,239.2	1,176.1	1,240.6
Dilutive effect of outstanding common stock options and RSUs	8.9	11.5	9.7	11.5
Weighted average common and common equivalent shares outstanding (for diluted calculation)	1,180.7	1,250.7	1,185.8	1,252.1
Earnings per share - basic	$ 0.28	$ 0.54	$ 1.03	$ 1.15
Earnings per share - diluted	$ 0.28	$ 0.53	$ 1.02	$ 1.14