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. 27, 2020	Jun. 28, 2020	Mar. 29, 2020	Dec. 29, 2019	Sep. 29, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 30, 2018	Sep. 27, 2020	Sep. 29, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Net earnings attributable to Starbucks	$ 392.6	$ (678.4)	$ 328.4	$ 885.7	$ 802.9	$ 1,372.8	$ 663.2	$ 760.6	$ 928.3	$ 3,599.2	$ 4,518.3
Weighted average common shares and common stock units outstanding (for basic calculation)									1,172.8	1,221.2	1,382.7
Dilutive effect of outstanding common stock options and RSUs									9.0	12.0	11.9
Weighted average common and common equivalent shares outstanding (for diluted calculation)									1,181.8	1,233.2	1,394.6
Earnings Per Share, Basic									$ 0.79	$ 2.95	$ 3.27
Earnings/(loss) Per Share, Diluted	$ 0.33	$ (0.58)	$ 0.28	$ 0.74	$ 0.67	$ 1.12	$ 0.53	$ 0.61	$ 0.79	$ 2.92	$ 3.24