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
	Jan. 02, 2022	Dec. 27, 2020
Earnings Per Share [Abstract]
Net earnings attributable to Starbucks	$ 815.9	$ 622.2
Weighted average common shares outstanding (for basic calculation)	1,169.6	1,175.0
Dilutive effect of outstanding common stock options and RSUs	7.0	8.0
Weighted average common and common equivalent shares outstanding (for diluted calculation)	1,176.6	1,183.0
EPS — basic	$ 0.70	$ 0.53
EPS — diluted	$ 0.69	$ 0.53