Investments and Fair Value Measurements (Schedule Of Financial Assets Carried At Fair Value) (Details) - USD ($) $ in Thousands		12 Months Ended
		Sep. 24, 2021		Sep. 25, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash Equivalents, at Carrying Value		$ 1,225,380
Cash				$ 1,071,876
Short-term investments, cost		330,129		399,933
Short-term investments, unrealized gains		0
Short-term investments, unrealized losses		0		0
Short term investments, total		330,401		400,301
Total cash, cash equivalents, and investments, cost		1,326,765		1,169,983
Total cash, cash equivalents, and investments, unrealized gains		325		1,006
Total cash, cash equivalents, and investments, unrealized losses		(52)		(16)
Total cash, cash equivalents, and investments, total		1,327,038		1,170,973
Assets		1,225,380		1,071,876
Government bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash				125
Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash				900
Municipal debt securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total cash, cash equivalents, and investments, cost		7,031		2,505
Other long-term investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term investments		6,500		4,700
Short-term investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments, cost				46,703
Short-term investments, unrealized gains				248
Short-term investments, unrealized losses				(3)
Short term investments, total				46,948
Long-term investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments, cost				51,404
Short-term investments, unrealized gains				758
Short-term investments, unrealized losses				(13)
U.S. agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments, unrealized gains		6
Short-term investments, unrealized losses		0
Short term investments, total		1,102
Cash
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash Equivalents, at Carrying Value		990,182
Cash		990,182		856,740
Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash Equivalents, at Carrying Value		235,198
Cash		235,198		214,111
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash		1,225,380		1,070,976
Assets		1,230,448		1,073,979
Currency derivatives as hedge instruments, liabilities		0		0
Level 1 | Other Current Assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Currency derivatives as hedge instruments, assets		0		0
Level 1 | Other Noncurrent Assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Currency derivatives as hedge instruments, assets				0
Level 1 | Government bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash				125
Level 1 | Investments held in supplemental retirement plan:
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets		4,975		4,279
Liabilities		4,975		4,279
Level 1 | Cash
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash		990,182		856,740
Level 1 | Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash		235,198		214,111
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash		0		900
Assets		90,134		92,818
Currency derivatives as hedge instruments, liabilities		(197)		(79)
Level 2 | Other Current Assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Currency derivatives as hedge instruments, assets		689		4,267
Level 2 | Other Noncurrent Assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Currency derivatives as hedge instruments, assets				369
Level 2 | Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash				900
Level 2 | U.S. agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments		1,102
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets		0		0
Currency derivatives as hedge instruments, liabilities		0		0
Level 3 | Other Current Assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Currency derivatives as hedge instruments, assets		0		0
Level 3 | Other Noncurrent Assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Currency derivatives as hedge instruments, assets				0
Short-term investments | Government bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments, cost		100		5,118
Short-term investments, unrealized gains		2		47
Short-term investments, unrealized losses		0		0
Short term investments, total		102		5,165
Short-term investments | U.S. agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments, cost				999
Short-term investments | Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments, cost		5,184		4,727
Short-term investments, unrealized gains		2		4
Short-term investments, unrealized losses		0		0
Short term investments, total		5,186		4,731
Short-term investments | Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments, cost		18,850		18,754
Short-term investments, unrealized gains		116		87
Short-term investments, unrealized losses		0		(3)
Short term investments, total		18,966		18,838
Short-term investments | Municipal debt securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments, cost		11,660		14,828
Short-term investments, unrealized gains		29		97
Short-term investments, unrealized losses		(1)		0
Short term investments, total		11,688		14,925
Short-term investments | Short-term investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments, cost		38,685
Short-term investments, unrealized gains		155
Short-term investments, unrealized losses		(1)
Short term investments, total		38,839
Short-term investments | Certificates of Deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments, cost		1,795		2,277
Short-term investments, unrealized gains		0		1
Short-term investments, unrealized losses		0		0
Short term investments, total		1,795		2,278
Short-term investments | U.S. agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments, cost		1,096
Short-term investments, unrealized gains				12
Short-term investments, unrealized losses				0
Short term investments, total				1,011
Short-term investments | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments		102		1,370
Short-term investments | Level 1 | Government bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments		102		1,370
Short-term investments | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments		38,737		45,578
Short-term investments | Level 2 | Government bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments		0		3,795
Short-term investments | Level 2 | Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments		5,186		4,731
Short-term investments | Level 2 | Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments		18,966		18,838
Short-term investments | Level 2 | Municipal debt securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments		11,688		14,925
Short-term investments | Level 2 | Certificates of Deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments		1,795		2,278
Short-term investments | Level 2 | U.S. agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments				1,011
Long-term investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short term investments, total				52,149
Long-term investments | Government bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments, cost		11,784		5,137
Short-term investments, unrealized gains		38		80
Short-term investments, unrealized losses		(16)		0
Short term investments, total		11,806		5,217
Long-term investments | U.S. agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments, cost		2,264		2,214
Short-term investments, unrealized gains		13		56
Short-term investments, unrealized losses		(2)		0
Short term investments, total		2,275		2,270
Long-term investments | Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments, cost		32,116		24,657
Short-term investments, unrealized gains		61		419
Short-term investments, unrealized losses		(25)		(7)
Short term investments, total		32,152		25,069
Long-term investments | Municipal debt securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments, cost		10,080		15,220
Short-term investments, unrealized gains		58		203
Short-term investments, unrealized losses		(8)		(6)
Short term investments, total		10,130		15,417
Long-term investments | Other long-term investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments, cost		6,456	[1]	4,176	[2]
Short-term investments, unrealized gains		0	[1]	0	[2]
Short-term investments, unrealized losses		0	[1]	0	[2]
Short term investments, total		6,456	[1]	4,176	[2]
Long-term investments | Long-term investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments, cost		62,700
Short-term investments, unrealized gains		170
Short-term investments, unrealized losses		(51)
Short term investments, total		62,819
Long-term investments | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term investments		4,966		1,633
Long-term investments | Level 1 | Government bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term investments		4,966		1,633
Long-term investments | Level 1 | Other long-term investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term investments	[2]			0
Long-term investments | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term investments		51,397		46,340
Long-term investments | Level 2 | Government bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term investments		6,840		3,584
Long-term investments | Level 2 | U.S. agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term investments		2,275		2,270
Long-term investments | Level 2 | Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term investments		32,152		25,069
Long-term investments | Level 2 | Municipal debt securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term investments		10,130		15,417
Liabilities: Included in other accrued liabilities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Currency derivatives as hedge instruments, unrealized gains		0		0
Currency derivatives as hedge instruments, unrealized loss		(197)		(79)
Currency derivatives as hedge instruments, liabilities, cost		0		0
Currency derivatives as hedge instruments, liabilities		(197)		(79)
Assets: Included in other current assets | Other Current Assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Currency derivatives as hedge instruments, assets, cost		0		0
Currency derivatives as hedge instruments, unrealized gains		689		4,267
Currency derivatives as hedge instruments, unrealized loss		0		0
Currency derivatives as hedge instruments, assets		$ 689		4,267
Assets: Included in other current assets | Other Noncurrent Assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Currency derivatives as hedge instruments, assets, cost				0
Currency derivatives as hedge instruments, unrealized gains				369
Currency derivatives as hedge instruments, unrealized loss				0
Currency derivatives as hedge instruments, assets				$ 369

[1] Other long-term investments as of September 24, 2021 is comprised of one equity method investment which is not carried at fair value of $6.5 million.

[2] Other long-term investments as of September 25, 2020 is comprised of one equity method investment which is not carried at fair value of $4.7 million.