Fair Value Measurements (Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Apr. 01, 2018	Apr. 01, 2018	Apr. 02, 2017	Oct. 01, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment		$ 28.5	$ 0.0
Assets:
Total short-term investments	$ 100.5	100.5		$ 228.6
Available-for-sale securities	293.1	293.1		542.3
Total Assets	2,560.6	2,560.6		3,271.0
Liabilities:
Total Liabilities	82.8	82.8		38.5
Goodwill	3,793.5	3,793.5		1,539.2
Intangible Assets, Net (Excluding Goodwill)	1,228.4	1,228.4		441.4
Cash and Cash Equivalents [Member]
Assets:
Cash and cash equivalents	2,142.0	2,142.0		2,462.3
Short-term Investments [Member]
Assets:
Available-for-sale securities	31.3	31.3		151.7
Trading securities	69.2	69.2		76.9
Total short-term investments	100.5	100.5		228.6
Prepaid Expenses and Other Current Assets [Member]
Assets:
Derivative assets	23.4	23.4		13.4
Long-term Investments [Member]
Assets:
Available-for-sale securities	293.1	293.1		542.3
Other Long-Term Assets [Member]
Assets:
Derivative assets	1.6	1.6		24.4
Accrued Liabilities [Member]
Liabilities:
Derivative liabilities	18.7	18.7		16.4
Other Long-Term Liabilities [Member]
Liabilities:
Derivative liabilities	64.1	64.1		22.1
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets:
Total Assets	2,324.8	2,324.8		2,748.1
Liabilities:
Total Liabilities	2.5	2.5		2.5
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Cash and Cash Equivalents [Member]
Assets:
Cash and cash equivalents	2,142.0	2,142.0		2,462.3
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities	10.5	10.5		81.4
Trading securities	69.2	69.2		76.9
Total short-term investments	79.7	79.7		158.3
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Prepaid Expenses and Other Current Assets [Member]
Assets:
Derivative assets	0.3	0.3		0.1
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	102.8	102.8		127.4
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other Long-Term Assets [Member]
Assets:
Derivative assets	0.0	0.0		0.0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Accrued Liabilities [Member]
Liabilities:
Derivative liabilities	2.5	2.5		2.5
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other Long-Term Liabilities [Member]
Liabilities:
Derivative liabilities	0.0	0.0		0.0
Significant Other Observable Inputs (Level 2) [Member]
Assets:
Total Assets	229.9	229.9		517.0
Liabilities:
Total Liabilities	80.3	80.3		36.0
Significant Other Observable Inputs (Level 2) [Member] | Cash and Cash Equivalents [Member]
Assets:
Cash and cash equivalents	0.0	0.0		0.0
Significant Other Observable Inputs (Level 2) [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities	20.8	20.8		70.3
Trading securities	0.0	0.0		0.0
Total short-term investments	20.8	20.8		70.3
Significant Other Observable Inputs (Level 2) [Member] | Prepaid Expenses and Other Current Assets [Member]
Assets:
Derivative assets	23.1	23.1		13.3
Significant Other Observable Inputs (Level 2) [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	184.4	184.4		409.0
Significant Other Observable Inputs (Level 2) [Member] | Other Long-Term Assets [Member]
Assets:
Derivative assets	1.6	1.6		24.4
Significant Other Observable Inputs (Level 2) [Member] | Accrued Liabilities [Member]
Liabilities:
Derivative liabilities	16.2	16.2		13.9
Significant Other Observable Inputs (Level 2) [Member] | Other Long-Term Liabilities [Member]
Liabilities:
Derivative liabilities	64.1	64.1		22.1
Significant Unobservable Inputs (Level 3) [Member]
Assets:
Total Assets	5.9	5.9		5.9
Liabilities:
Total Liabilities	0.0	0.0		0.0
Significant Unobservable Inputs (Level 3) [Member] | Cash and Cash Equivalents [Member]
Assets:
Cash and cash equivalents	0.0	0.0		0.0
Significant Unobservable Inputs (Level 3) [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities	0.0	0.0		0.0
Trading securities	0.0	0.0		0.0
Total short-term investments	0.0	0.0		0.0
Significant Unobservable Inputs (Level 3) [Member] | Prepaid Expenses and Other Current Assets [Member]
Assets:
Derivative assets	0.0	0.0		0.0
Significant Unobservable Inputs (Level 3) [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	5.9	5.9		5.9
Significant Unobservable Inputs (Level 3) [Member] | Other Long-Term Assets [Member]
Assets:
Derivative assets	0.0	0.0		0.0
Significant Unobservable Inputs (Level 3) [Member] | Accrued Liabilities [Member]
Liabilities:
Derivative liabilities	0.0	0.0		0.0
Significant Unobservable Inputs (Level 3) [Member] | Other Long-Term Liabilities [Member]
Liabilities:
Derivative liabilities	0.0	0.0		0.0
Agency Obligations [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities				7.5
Agency Obligations [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	8.4	8.4		21.8
Agency Obligations [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities				0.0
Agency Obligations [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	0.0	0.0		0.0
Agency Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities				7.5
Agency Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	8.4	8.4		21.8
Agency Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities				0.0
Agency Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	0.0	0.0		0.0
Commercial Paper [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities				2.0
Commercial Paper [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities				0.0
Commercial Paper [Member] | Significant Other Observable Inputs (Level 2) [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities				2.0
Commercial Paper [Member] | Significant Unobservable Inputs (Level 3) [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities				0.0
Corporate Debt Securities [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities	19.0	19.0		49.4
Corporate Debt Securities [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	126.8	126.8		207.4
Corporate Debt Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities	0.0	0.0		0.0
Corporate Debt Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	0.0	0.0		0.0
Corporate Debt Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities	19.0	19.0		49.4
Corporate Debt Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	126.8	126.8		207.4
Corporate Debt Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities	0.0	0.0		0.0
Corporate Debt Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	0.0	0.0		0.0
Foreign Government Obligations [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities				7.1
Foreign Government Obligations [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	12.1	12.1		17.1
Foreign Government Obligations [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities				0.0
Foreign Government Obligations [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	0.0	0.0		0.0
Foreign Government Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities				7.1
Foreign Government Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	12.1	12.1		17.1
Foreign Government Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities				0.0
Foreign Government Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	0.0	0.0		0.0
U.S. Government Treasury Securities [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities	10.5	10.5		81.4
U.S. Government Treasury Securities [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	102.8	102.8		127.4
U.S. Government Treasury Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities	10.5	10.5		81.4
U.S. Government Treasury Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	102.8	102.8		127.4
U.S. Government Treasury Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities	0.0	0.0		0.0
U.S. Government Treasury Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	0.0	0.0		0.0
U.S. Government Treasury Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities	0.0	0.0		0.0
U.S. Government Treasury Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	0.0	0.0		0.0
State and Local Government Obligations [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities				2.0
State and Local Government Obligations [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	4.8	4.8		7.0
State and Local Government Obligations [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities				0.0
State and Local Government Obligations [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	0.0	0.0		0.0
State and Local Government Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities				2.0
State and Local Government Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	4.8	4.8		7.0
State and Local Government Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities				0.0
State and Local Government Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	0.0	0.0		0.0
Certificates of Deposit [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities				2.3
Certificates of Deposit [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities				0.0
Certificates of Deposit [Member] | Significant Other Observable Inputs (Level 2) [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities				2.3
Certificates of Deposit [Member] | Significant Unobservable Inputs (Level 3) [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities				0.0
Auction Rate Securities [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	5.9	5.9		5.9
Auction Rate Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	0.0	0.0		0.0
Auction Rate Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	0.0	0.0		0.0
Auction Rate Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	5.9	5.9		5.9
Mortgage and Other Asset-backed Securities [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities	1.8	1.8
Mortgage and Other Asset-backed Securities [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	32.3	32.3		155.7
Mortgage and Other Asset-backed Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities	0.0	0.0
Mortgage and Other Asset-backed Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	0.0	0.0		0.0
Mortgage and Other Asset-backed Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities	1.8	1.8
Mortgage and Other Asset-backed Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	32.3	32.3		155.7
Mortgage and Other Asset-backed Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Short-term Investments [Member]
Assets:
Available-for-sale securities	0.0	0.0
Mortgage and Other Asset-backed Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Long-term Investments [Member]
Assets:
Available-for-sale securities	0.0	$ 0.0		$ 0.0
Starbucks Coffee Switzerland [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment	$ 28.5