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. 29, 2013	Sep. 28, 2012
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 months	$ 97,015	$ 119,981
Gross Unrealized Losses, Less than 12 months	60	(59)
Fair Value, 12 months or greater	1,583	5,565
Gross Unrealized Losses, 12 months or greater	1	(1)
Fair Value	98,598	125,546
Gross Unrealized Losses	61	(60)
U.S. Agency Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 months	14,061	6,999
Gross Unrealized Losses, Less than 12 months	5	(3)
Fair Value, 12 months or greater	0	0
Gross Unrealized Losses, 12 months or greater	0	0
Fair Value	14,061	6,999
Gross Unrealized Losses	5	(3)
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 months	24,670	25,277
Gross Unrealized Losses, Less than 12 months	12	(19)
Fair Value, 12 months or greater	0	0
Gross Unrealized Losses, 12 months or greater	0	0
Fair Value	24,670	25,277
Gross Unrealized Losses	12	(19)
Municipal debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 months	58,284	87,705
Gross Unrealized Losses, Less than 12 months	43	(37)
Fair Value, 12 months or greater	1,583	5,565
Gross Unrealized Losses, 12 months or greater	1	(1)
Fair Value	59,867	93,270
Gross Unrealized Losses	$ 44	$ (38)