v2.4.0.6
Fair Value Of Financial Instruments (Schedule Of Cash And Marketable Securities) (Details) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2011
Mar. 26, 2011
Schedule of Trading Securities and Other Trading Assets [Line Items]    
Amortized Cost $ 160,394 $ 215,037
Gross Unrealized Gains 24 65
Gross Unrealized Losses (76) (47)
Estimated Fair Value (Net Carrying Amount) 160,342 215,055
Cash And Cash Equivalents [Member]
   
Schedule of Trading Securities and Other Trading Assets [Line Items]    
Amortized Cost 11,666 9,626
Estimated Fair Value (Net Carrying Amount) 11,666 9,626
Money-Market Funds [Member]
   
Schedule of Trading Securities and Other Trading Assets [Line Items]    
Amortized Cost 27,220 17,700
Estimated Fair Value (Net Carrying Amount) 27,220 17,700
Corporate Debt Securities [Member]
   
Schedule of Trading Securities and Other Trading Assets [Line Items]    
Amortized Cost 59,694 64,227
Gross Unrealized Gains 10 23
Gross Unrealized Losses (64) (38)
Estimated Fair Value (Net Carrying Amount) 59,640 64,212
U.S. Treasury Securities [Member]
   
Schedule of Trading Securities and Other Trading Assets [Line Items]    
Amortized Cost 24,143 45,768
Gross Unrealized Gains 4 13
Estimated Fair Value (Net Carrying Amount) 24,147 45,781
Agency Discount Notes [Member]
   
Schedule of Trading Securities and Other Trading Assets [Line Items]    
Amortized Cost 17,831 16,588
Gross Unrealized Gains 8 5
Gross Unrealized Losses (1) (2)
Estimated Fair Value (Net Carrying Amount) 17,838 16,591
Commercial Paper [Member]
   
Schedule of Trading Securities and Other Trading Assets [Line Items]    
Amortized Cost 19,840 61,128
Gross Unrealized Gains 2 24
Gross Unrealized Losses (11) (7)
Estimated Fair Value (Net Carrying Amount) $ 19,831 $ 61,145