Fair Value Measurements (Tables)

9 Months Ended

12 Months Ended

Jun. 28, 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 June 28, 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	$	3,965.9	$	3,965.9	$	—	$	—
Short-term investments:
Available-for-sale debt securities
Commercial paper	37.6		—		37.6		—
Corporate debt securities	106.0		—		106.0		—
Foreign government obligations	8.5		—		8.5		—
Mortgage and other asset-backed securities	11.8		—		11.8		—
Certificates of deposit	6.2		—		6.2		—
Total available-for-sale debt securities	170.1		—		170.1		—
Marketable equity securities	59.8		59.8		—		—
Total short-term investments	229.9		59.8		170.1		—
Prepaid expenses and other current assets:
Derivative assets	20.7		0.3		20.4		—
Long-term investments:
Available-for-sale debt securities
Corporate debt securities	90.6		—		90.6		—
Auction rate securities	5.7		—		—		5.7
U.S. government treasury securities	98.9		98.9		—		—
State and local government obligations	3.6		—		3.6		—
Mortgage and other asset-backed securities	24.6		—		24.6		—
Total long-term investments	223.4		98.9		118.8		5.7
Other long-term assets:
Derivative assets	97.9		—		97.9		—
Total assets	$	4,537.8	$	4,124.9	$	407.2	$	5.7
Liabilities:
Accrued liabilities:
Derivative liabilities	$	21.3	$	14.1	$	7.2	$	—
Other long-term liabilities:
Derivative liabilities	80.0		0.1		79.9		—
Total liabilities	$	101.3	$	14.2	$	87.1	$	—

			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
Corporate debt securities	101.2		—		101.2		—
Auction rate securities	5.8		—		—		5.8
U.S. government treasury securities	106.5		106.5		—		—
State and local government obligations	4.9		—		4.9		—
Mortgage and other asset-backed	1.6		—		1.6		—
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 liabilities	$	18.2	$	1.1	$	17.1	$	—