Selected Quarterly Financial Information (Schedule of Selected Quarterly Financial Information) (Details) - USD ($) $ / shares in Units, $ 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
Selected Quarterly Financial Information [Abstract]
Revenues	$ 6,203.1	$ 4,222.1	$ 5,995.7	$ 7,097.1	$ 6,747.0	$ 6,823.0	$ 6,305.9	$ 6,632.7	$ 23,518.0	$ 26,508.6	$ 24,719.5
Operating income/(loss)	558.3	(703.9)	487.4	1,219.8	1,083.3	1,121.3	857.7	1,015.7	1,561.7	4,077.9	3,883.3
Net earnings/(loss) 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
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