Composition Of Certain Financial Statement Captions (Schedule Of Investment Portfolio Recorded As Cash Equivalents, Short-Term Investments, And Long-Term Investments) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 27, 2013		Sep. 27, 2013
Investment Holdings [Line Items]
Cost	$ 478,367	[1]	$ 477,625	[1]
Unrealized Gain	792	[1]	715	[1]
Unrealized Loss	(321)	[1]	(407)	[1]
Estimated Fair Value	478,838	[1]	477,933	[1]
U.S. Agency Securities [Member]
Investment Holdings [Line Items]
Cost	58,085		60,126
Unrealized Gain	14		16
Unrealized Loss	(52)		(76)
Estimated Fair Value	58,047		60,066
Commercial Paper [Member]
Investment Holdings [Line Items]
Cost	20,618		10,991
Unrealized Gain	0		0
Unrealized Loss	0		0
Estimated Fair Value	20,618		10,991
Corporate Bonds [Member]
Investment Holdings [Line Items]
Cost	123,821		134,097
Unrealized Gain	290		315
Unrealized Loss	(158)		(174)
Estimated Fair Value	123,953		134,238
Municipal Bonds [Member]
Investment Holdings [Line Items]
Cost	273,030		256,218
Unrealized Gain	488		384
Unrealized Loss	(111)		(157)
Estimated Fair Value	273,407		256,445
Money Market Funds [Member]
Investment Holdings [Line Items]
Cost	2,813		16,193
Unrealized Gain	0		0
Unrealized Loss	0		0
Estimated Fair Value	$ 2,813		$ 16,193

[1] September 27, 2013 CostUnrealizedGainsUnrealizedLossesEstimated Fair ValueMoney market funds$16,193$—$—$16,193U.S. agency securities60,12616(76)60,066Commercial paper10,991——10,991Corporate bonds134,097315(174)134,238Municipal debt securities256,218384(157)256,445Cash equivalents and investments (1)$477,625$715$(407)$477,933