v2.4.0.6
Fair Value Measurements (Schedule Of Financial Assets Carried At Fair Value) (Details) (USD $)
In Thousands, unless otherwise specified
Mar. 30, 2012
Sep. 30, 2011
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Financial assets carried at fair value $ 827,042 $ 823,007
Level 1 [Member]
   
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Financial assets carried at fair value 291,595 173,848
Level 2 [Member]
   
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Financial assets carried at fair value 535,447 649,159
Level 3 [Member]
   
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Financial assets carried at fair value      
Corporate Bonds [Member]
   
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Financial assets carried at fair value 125,092 [1] 176,958 [1]
Corporate Bonds [Member] | Level 1 [Member]
   
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Financial assets carried at fair value    [1]    [1]
Corporate Bonds [Member] | Level 2 [Member]
   
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Financial assets carried at fair value 125,092 [1] 176,958 [1]
Corporate Bonds [Member] | Level 3 [Member]
   
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Financial assets carried at fair value    [1]    [1]
Municipal debt securities [Member]
   
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Financial assets carried at fair value 389,371 [1] 472,201 [1]
Municipal debt securities [Member] | Level 1 [Member]
   
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Financial assets carried at fair value    [1]    [1]
Municipal debt securities [Member] | Level 2 [Member]
   
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Financial assets carried at fair value 389,371 [1] 472,201 [1]
Municipal debt securities [Member] | Level 3 [Member]
   
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Financial assets carried at fair value    [1]    [1]
U.S. Agency Securities [Member]
   
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Financial assets carried at fair value 25,092 [1],[2] 29,919 [1],[2]
U.S. Agency Securities [Member] | Level 1 [Member]
   
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Financial assets carried at fair value 25,092 [1],[2] 29,919 [1],[2]
U.S. Agency Securities [Member] | Level 2 [Member]
   
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Financial assets carried at fair value    [1],[2]    [1],[2]
U.S. Agency Securities [Member] | Level 3 [Member]
   
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Financial assets carried at fair value    [1],[2]    [1],[2]
Money Market Funds [Member]
   
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Financial assets carried at fair value 264,366 [2] 142,038 [2]
Money Market Funds [Member] | Level 1 [Member]
   
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Financial assets carried at fair value 264,366 [2] 142,038 [2]
Money Market Funds [Member] | Level 2 [Member]
   
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Financial assets carried at fair value    [2]    [2]
Money Market Funds [Member] | Level 3 [Member]
   
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Financial assets carried at fair value    [2]    [2]
Commercial Paper [Member]
   
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Financial assets carried at fair value 20,984 [3]  
Commercial Paper [Member] | Level 1 [Member]
   
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Financial assets carried at fair value    [3]  
Commercial Paper [Member] | Level 2 [Member]
   
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Financial assets carried at fair value 20,984 [3]  
Commercial Paper [Member] | Level 3 [Member]
   
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Financial assets carried at fair value    [3]  
Investments Held In Supplemental Retirement Plan [Member]
   
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Financial assets carried at fair value 2,137 [4] 1,891 [4]
Investments Held In Supplemental Retirement Plan [Member] | Level 1 [Member]
   
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Financial assets carried at fair value 2,137 [4] 1,891 [4]
Investments Held In Supplemental Retirement Plan [Member] | Level 2 [Member]
   
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Financial assets carried at fair value    [4]    [4]
Investments Held In Supplemental Retirement Plan [Member] | Level 3 [Member]
   
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Financial assets carried at fair value    [4]    [4]
[1] These assets are included within short-term investments and within long-term investments.
[2] These assets are included within cash and cash equivalents.
[3] These assets are included within short-term investments.
[4] These assets are included within prepaid expenses and other current assets and within other non-current assets.