Composition Of Certain Financial Statement Captions (Schedule Of Gross Unrealized Losses And The Fair Value For Available-For-Sale Securities) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 30, 2012	Sep. 30, 2011
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	29
Fair Value, Less than 12 months	$ 72,696	$ 171,076
Gross Unrealized Losses, Less than 12 months	(56)	(543)
Fair Value, 12 months or greater	0	2,081
Gross Unrealized Losses, 12 months or greater	0	(3)
Fair Value	72,696	173,157
Gross Unrealized Losses	(56)	(546)
U.S. Agency Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 months		3,997
Gross Unrealized Losses, Less than 12 months		(4)
Fair Value, 12 months or greater		0
Gross Unrealized Losses, 12 months or greater		0
Fair Value		3,997
Gross Unrealized Losses		(4)
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 months	15,642	87,613
Gross Unrealized Losses, Less than 12 months	(13)	(487)
Fair Value, 12 months or greater	0	0
Gross Unrealized Losses, 12 months or greater	0	0
Fair Value	15,642	87,613
Gross Unrealized Losses	(13)	(487)
Municipal debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 months	57,054	79,466
Gross Unrealized Losses, Less than 12 months	(43)	(52)
Fair Value, 12 months or greater	0	2,081
Gross Unrealized Losses, 12 months or greater	0	(3)
Fair Value	57,054	81,547
Gross Unrealized Losses	$ (43)	$ (55)