| Consolidated Statements of Earnings - USD ($) shares in Millions, $ in Millions | 12 Months Ended | | | | | Horizontal Analysis | | | | | | Verical Analysis |
| | Sep. 30, 2018 | Sep. 29, 2019 | Sep. 27, 2020 | | | 2019 | 2020 | 2019 | 2020 | | | 2018 | 2019 | 2020 | | | | | | | | Sep. 30, 2018 | | Sep. 27, 2020 |
| Net Revenues: |
| Company-operated stores | $ 19,690.3 | $ 21,544.4 | $ 19,164.6 | | | $ 1,854.1 | $ (2,379.8) | 9.42% | -11.05% | | | 79.65% | 81.27% | 81.49% | | | | | | | | $ 19,690.3 | | $ 19,164.6 |
| Licensed stores | 2,652.2 | 2,875.0 | 2,327.1 | | | 222.8 | (547.9) | 8.40% | -19.06% | | | 10.73% | 10.85% | 9.89% | | | | | | | | $ 2,652.2 | | $ 2,327.1 |
| Other | 2,377.0 | 2,089.2 | 2,026.3 | | | (287.8) | (62.9) | -12.11% | -3.01% | | | 9.62% | 7.88% | 8.62% | | | | | | | | $ 2,377.0 | | $ 2,026.3 |
| Total Net Revenues | 24,719.5 | 26,508.6 | 23,518.0 | | | 1,789.1 | (2,990.6) | 7.24% | -11.28% | | | 100% | 100% | 100% | | | | | | | | $ 24,719.5 | | $ 23,518 |
| Product and distribution costs | 7,930.7 | 8,526.9 | 7,694.9 | | | 596.2 | (832.0) | 7.52% | -9.76% | | | 32.08% | 32.17% | 32.72% | | | | | | | | 7,930.7 | | 7,694.9 |
| Store operating expenses | 9,472.2 | 10,493.6 | 10,764.0 | | | 1,021.4 | 270.4 | 10.78% | 2.58% | | | 38.32% | 39.59% | 45.77% | | | | | | | | 9,472.2 | | 10,764 |
| Other operating expenses | 554.9 | 371.0 | 430.3 | | | (183.9) | 59.3 | -33.14% | 15.98% | | | 2.24% | 1.40% | 1.83% | | | | | | | | 554.9 | | 430.3 |
| Depreciation and amortization expenses | 1,247.0 | 1,377.3 | 1,431.3 | | | 130.3 | 54.0 | 10.45% | 3.92% | | | 5.04% | 5.20% | 6.09% | | | | | | | | 1,247 | | 1,431.3 |
| General and administrative expenses | 1,708.2 | 1,824.1 | 1,679.6 | | | 115.9 | (144.5) | 6.78% | -7.92% | | | 6.91% | 6.88% | 7.14% | | | | | | | | 1,708.2 | | 1,679.6 |
| Restructuring and impairments | 224.4 | 135.8 | 278.7 | | | (88.6) | 142.9 | -39.48% | 105.23% | | | 0.91% | 0.51% | 1.19% | | | | | | | | 224.4 | | 278.7 |
| Total operating expenses | 21,137.4 | 22,728.7 | 22,278.8 | | | 1,591.3 | (449.9) | 7.53% | -1.98% | | | 85.51% | 85.74% | 94.73% | | | | | | | | 21,137.4 | | 22,278.8 |
| Income from equity investees | 301.2 | 298.0 | 322.5 | | | (3.2) | 24.5 | -1.06% | 8.22% | | | 1.22% | 1.12% | 1.37% | | | | | | | | 301.2 | | 322.5 |
| Operating income | 3,883.3 | 4,077.9 | 1,561.7 | | | 194.6 | (2,516.2) | 5.01% | -61.70% | | | 15.71% | 15.38% | 6.64% | | | | | | | | 3,883.3 | | 1,561.7 |
| Gain resulting from acquisition of joint venture | 1,376.4 | 0.0 | 0.0 | | | (1,376.4) | 0.0 | -100.00% | 0.00% | | | 5.57% | 0.00% | 0.00% | | | | | | | | 1,376.4 | | 0 |
| Net gain resulting from divestiture of certain retail operations | 499.2 | 622.8 | 0.0 | | | 123.6 | (622.8) | 24.76% | -100.00% | | | 2.02% | 2.35% | 0.00% | | | | | | | | 499.2 | | 0 |
| Interest income and other, net | 191.4 | 96.5 | 39.7 | | | (94.9) | (56.8) | -49.58% | -58.86% | | | 0.77% | 0.36% | 0.17% | | | | | | | | 191.4 | | 39.7 |
| Interest expense | (170.3) | (331.0) | (437.0) | | | (160.7) | (106.0) | 94.36% | 32.02% | | | -0.69% | -1.25% | -1.86% | | | | | | | | (170.3) | | (437) |
| Earnings before income taxes | 5,780.0 | 4,466.2 | 1,164.4 | | | (1,313.8) | (3,301.8) | -22.73% | -73.93% | | | 23.38% | 16.85% | 4.95% | | | | | | | | 5,780 | | 1,164.4 |
| Income tax expense | 1,262.0 | 871.6 | 239.7 | | | (390.4) | (631.9) | -30.94% | -72.50% | | | 5.11% | 3.29% | 1.02% | | | | | | | | 1,262 | | 239.7 |
| Net earnings including noncontrolling interests | 4,518.0 | 3,594.6 | 924.7 | | | (923.4) | (2,669.9) | -20.44% | -74.28% | | | 18.28% | 13.56% | 3.93% | | | | | | | | 4,518 | | 924.7 |
| Net loss attributable to noncontrolling interest | (0.3) | (4.6) | (3.6) | | | (4.3) | 1.0 | 1433.33% | -21.74% | | | -0.00% | -0.02% | -0.02% | | | | | | | | (0.3) | | (3.6) |
| Net earnings attributable to Starbucks | 4,518.3 | 3,599.2 | 928.3 | | | (919.1) | (2,670.9) | -20.34% | -74.21% | | | 18.28% | 13.58% | 3.95% | | | | | | | | $ 4,518.3 | | $ 928.3 |
| Earnings Per Share, Basic | 3.3 | 3.0 | 0.8 | | | (0.3) | (2.2) | -9.79% | -73.22% | | | 0.01% | 0.01% | 0.00% | | | | | | | | $ 3.27 | | $ 0.79 |
| Earnings/(loss) Per Share, Diluted | 3.2 | 2.9 | 0.8 | | | (0.3) | (2.1) | -9.88% | -72.95% | | | 0.01% | 0.01% | 0.00% | | | | | | | | $ 3.24 | | $ 0.79 |
| Weighted average shares outstanding: | | | | | | | | | | | | 0.00% | 0.00% | 0.00% |
| Basic | 1,382.7 | 1,221.2 | 1,172.8 | | | (161.5) | (48.4) | -11.68% | -3.96% | | | 5.59% | 4.61% | 4.99% | | | | | | | | 1,382.7 | | 1,172.8 |
| Diluted | 1,394.6 | 1,233.2 | 1,181.8 | | | (161.4) | (51.4) | -11.57% | -4.17% | | | 5.64% | 4.65% | 5.03% | | | | | | | | 1,394.6 | | 1,181.8 |
| Product and Service, Other [Member] |
| Net Revenues: |
| Revenues | $ 2,377 | $ 2,089.2 | $ 2,026.3 | | | | | | | | | | | | | | | | | | | $ 2,377 | | $ 2,026.3 |
| Company-operated stores [Member] |
| Net Revenues: |
| Revenues | 19,690.3 | 21,544.4 | 19,690.3 | | | | | | | | | | | | | | | | | | | 19,690.3 | | 19,164.6 |
| Licensed stores [Member] |
| Net Revenues: |
| Revenues | $ 2,652.2 | $ 2,875 | $ 2,652.2 | | | | | | | | | | | | | | | | | | | $ 2,652.2 | | $ 2,327.1 |