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. 31, 2019	Apr. 01, 2018	Mar. 31, 2019	Apr. 01, 2018
Earnings Per Share [Abstract]
Document Period End Date			Mar. 31, 2019
Net earnings attributable to Starbucks	$ 663.2	$ 660.1	$ 1,423.6	$ 2,910.3
Weighted average common shares outstanding (for basic calculation)	1,239.2	1,394.9	1,240.6	1,407.9
Dilutive effect of outstanding common stock options and RSUs	11.5	11.7	11.5	12.6
Weighted average common and common equivalent shares outstanding (for diluted calculation)	1,250.7	1,406.6	1,252.1	1,420.5
Earnings per share - basic	$ 0.54	$ 0.47	$ 1.15	$ 2.07
Earnings per share - diluted	$ 0.53	$ 0.47	$ 1.14	$ 2.05