Fair Value Measurements (Tables)

12 Months Ended

Sep. 30, 2018

Oct. 01, 2017

Fair Value Disclosures [Abstract]

Assets and Liabilities Measured at Fair Value on a Recurring Basis

			Fair Value Measurements at Reporting Date Using
	Balance at September 30, 2018		Quoted Prices in Active Markets for  Identical Assets (Level 1)		Significant  Other Observable  Inputs (Level 2)		Significant Unobservable  Inputs (Level 3)
Assets:
Cash and cash equivalents	$	8,756.3	$	8,756.3	$	—	$	—
Short-term investments:
Available-for-sale securities
Commercial paper	8.4		—		8.4		—
Corporate debt securities	91.8		—		91.8		—
Mortgage and other asset-backed securities	6.0		—		6.0		—
Total available-for-sale securities	106.2		—		106.2		—
Trading securities	75.3		75.3		—		—
Total short-term investments	181.5		75.3		106.2		—
Prepaid expenses and other current assets:
Derivative assets	24.5		1.2		23.3		—
Long-term investments:
Available-for-sale securities
Agency obligations	5.9		—		5.9		—
Corporate debt securities	114.5		—		114.5		—
Auction rate securities	5.9		—		—		5.9
Foreign government obligations	3.6		—		3.6		—
U.S. government treasury securities	108.1		108.1		—		—
State and local government obligations	4.8		—		4.8		—
Mortgage and other asset-backed securities	24.9		—		24.9		—
Total long-term investments	267.7		108.1		153.7		5.9
Other long-term assets:
Derivative assets	10.4		—		10.4		—
Total assets	$	9,240.4	$	8,940.9	$	293.6	$	5.9
Liabilities:
Accrued liabilities:
Derivative liabilities	$	6.5	$	0.4	$	6.1	$	—
Other long-term liabilities:
Derivative liabilities	43.5		—		43.5		—
Total liabilities	$	50.0	$	0.4	$	49.6	$	—

Assets and Liabilities Measured at Fair Value on a Recurring Basis (in millions):

			Fair Value Measurements at Reporting Date Using
	Balance at September 30, 2018		Quoted Prices in Active Markets for  Identical Assets (Level 1)		Significant  Other Observable  Inputs (Level 2)		Significant Unobservable  Inputs (Level 3)
Assets:
Cash and cash equivalents	$	8,756.3	$	8,756.3	$	—	$	—
Short-term investments:
Available-for-sale securities
Commercial paper	8.4		—		8.4		—
Corporate debt securities	91.8		—		91.8		—
Mortgage and other asset-backed securities	6.0		—		6.0		—
Total available-for-sale securities	106.2		—		106.2		—
Trading securities	75.3		75.3		—		—
Total short-term investments	181.5		75.3		106.2		—
Prepaid expenses and other current assets:
Derivative assets	24.5		1.2		23.3		—
Long-term investments:
Available-for-sale securities
Agency obligations	5.9		—		5.9		—
Corporate debt securities	114.5		—		114.5		—
Auction rate securities	5.9		—		—		5.9
Foreign government obligations	3.6		—		3.6		—
U.S. government treasury securities	108.1		108.1		—		—
State and local government obligations	4.8		—		4.8		—
Mortgage and other asset-backed securities	24.9		—		24.9		—
Total long-term investments	267.7		108.1		153.7		5.9
Other long-term assets:
Derivative assets	10.4		—		10.4		—
Total assets	$	9,240.4	$	8,940.9	$	293.6	$	5.9
Liabilities:
Accrued liabilities:
Derivative liabilities	$	6.5	$	0.4	$	6.1	$	—
Other long-term liabilities:
Derivative liabilities	43.5		—		43.5		—
Total liabilities	$	50.0	$	0.4	$	49.6	$	—

			Fair Value Measurements at Reporting Date Using
	Balance at Oct 1, 2017		Quoted Prices in Active Markets for  Identical Assets (Level 1)		Significant  Other Observable  Inputs (Level 2)		Significant Unobservable  Inputs (Level 3)
Assets:
Cash and cash equivalents	$	2,462.3	$	2,462.3	$	—	$	—
Short-term investments:
Available-for-sale securities
Agency obligations	7.5		—		7.5		—
Commercial paper	2.0		—		2.0		—
Corporate debt securities	49.4		—		49.4		—
Foreign government obligations	7.1		—		7.1		—
U.S. government treasury securities	81.4		81.4		—		—
State and local government obligations	2.0		—		2.0		—
Certificates of deposit	2.3		—		2.3		—
Total available-for-sale securities	151.7		81.4		70.3		—
Trading securities	76.9		76.9		—		—
Total short-term investments	228.6		158.3		70.3		—
Prepaid expenses and other current assets:
Derivative assets	13.4		0.1		13.3		—
Long-term investments:
Available-for-sale securities
Agency obligations	21.8		—		21.8		—
Corporate debt securities	207.4		—		207.4		—
Auction rate securities	5.9		—		—		5.9
Foreign government obligations	17.1		—		17.1		—
U.S. government treasury securities	127.4		127.4		—		—
State and local government obligations	7.0		—		7.0		—
Mortgage and other asset-backed securities	155.7		—		155.7		—
Total long-term investments	542.3		127.4		409.0		5.9
Other long-term assets:
Derivative assets	24.4		—		24.4		—
Total assets	$	3,271.0	$	2,748.1	$	517.0	$	5.9
Liabilities:
Accrued liabilities:
Derivative liabilities	$	16.4	$	2.5	$	13.9	$	—
Other long-term liabilities:
Derivative liabilities	22.1		—		22.1		—
Total	$	38.5	$	2.5	$	36.0	$	—