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	Dec. 28, 2012	Sep. 28, 2012
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 months	$ 160,705	$ 119,981
Gross Unrealized Losses, Less than 12 months	203	(59)
Fair Value, 12 months or greater	0	5,565
Gross Unrealized Losses, 12 months or greater	0	(1)
Fair Value	160,705	125,546
Gross Unrealized Losses	203	(60)
U.S. Agency Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 months	26,401	6,999
Gross Unrealized Losses, Less than 12 months	2	(3)
Fair Value, 12 months or greater	0	0
Gross Unrealized Losses, 12 months or greater	0	0
Fair Value	26,401	6,999
Gross Unrealized Losses	2	(3)
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 months	53,111	25,277
Gross Unrealized Losses, Less than 12 months	80	(19)
Fair Value, 12 months or greater	0	0
Gross Unrealized Losses, 12 months or greater	0	0
Fair Value	53,111	25,277
Gross Unrealized Losses	80	(19)
Municipal debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 months	81,193	87,705
Gross Unrealized Losses, Less than 12 months	121	(37)
Fair Value, 12 months or greater	0	5,565
Gross Unrealized Losses, 12 months or greater	0	(1)
Fair Value	81,193	93,270
Gross Unrealized Losses	$ 121	$ (38)