Fair Value Measurements (Tables)

12 Months Ended

Sep. 27, 2020

Sep. 29, 2019

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 27, 2020		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	$	4,350.9	$	4,350.9	$	—	$	—
Short-term investments:
Available-for-sale debt securities
Certificates of deposit	1.6		—		1.6		—
Commercial paper	66.8		—		66.8		—
Corporate debt securities	123.6		—		123.6		—
Foreign government obligations	8.5		—		8.5		—
Mortgage and other asset-backed securities	15.8		—		15.8		—
Total available-for-sale debt securities	216.3		—		216.3		—
Marketable equity securities	64.9		64.9		—		—
Total short-term investments	281.2		64.9		216.3		—
Prepaid expenses and other current assets:
Derivative assets	15.6		3.6		12.0		—
Long-term investments:
Available-for-sale debt securities
Auction rate securities	5.7		—		—		5.7
Corporate debt securities	82.6		—		82.6		—
Mortgage and other asset-backed securities	19.3		—		19.3		—
State and local government obligations	3.6		—		3.6		—
U.S. government treasury securities	94.9		94.9		—		—
Total long-term investments	206.1		94.9		105.5		5.7
Other long-term assets:
Derivative assets	87.3		—		87.3		—
Total assets	$	4,941.1	$	4,514.3	$	421.1	$	5.7
Liabilities:
Accrued liabilities:
Derivative liabilities	$	7.3	$	1.9	$	5.4	$	—
Other long-term liabilities:
Derivative liabilities	79.3		0.1		79.2		—
Total liabilities	$	86.6	$	2.0	$	84.6	$	—

			Fair Value Measurements at Reporting Date Using
	Balance at September 29, 2019		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	$	2,686.6	$	2,686.6	$	—	$	—
Short-term investments:
Available-for-sale debt securities
Commercial paper	0.5		—		0.5		—
Corporate debt securities	3.5		—		3.5		—
Total available-for-sale debt securities	4.0		—		4.0		—
Marketable equity securities	66.5		66.5		—		—
Total short-term investments	70.5		66.5		4.0		—
Prepaid expenses and other current assets:
Derivative assets	12.6		—		12.6		—
Long-term investments:
Available-for-sale debt securities
Auction rate securities	5.8		—		—		5.8
Corporate debt securities	101.2		—		101.2		—
Mortgage and other asset-backed securities	1.6		—		1.6		—
State and local government obligations	4.9		—		4.9		—
U.S. government treasury securities	106.5		106.5		—		—
Total long-term investments	220.0		106.5		107.7		5.8
Other long-term assets:
Derivative assets	26.3		—		26.3		—
Total assets	$	3,016.0	$	2,859.6	$	150.6	$	5.8
Liabilities:
Accrued liabilities:
Derivative liabilities	$	5.7	$	1.1	$	4.6	$	—
Other long-term liabilities:
Derivative liabilities	12.5		—		12.5		—
Total	$	18.2	$	1.1	$	17.1	$	—