v2.4.0.6
Summary of Short-term and Non-current Investments by Maturity Date (Detail) (USD $)
In Millions, unless otherwise specified
Jan. 28, 2012
Jul. 30, 2011
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale investments maturities less than 1 year $ 54.7 $ 54.1
Available-for-sale investments maturities 1 to 3 years 109.0 102.7
Available-for-sale investments maturities over 3 years 35.0 35.8
Available-for-sale investments, Total 198.7 192.6
Available-for-sale investments - short-term
   
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale investments maturities less than 1 year 50.7 54.1
Available-for-sale investments, Total 50.7 54.1
Available-for-sale investments - short-term | Municipal bonds
   
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale investments maturities less than 1 year 48.0 52.7
Available-for-sale investments, Total 48.0 52.7
Available-for-sale investments - short-term | Restricted cash
   
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale investments maturities less than 1 year 2.7 1.4
Available-for-sale investments, Total 2.7 1.4
Available-for-sale investments - non-current
   
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale investments maturities 1 to 3 years 109.0 102.7
Available-for-sale investments maturities over 3 years 35.0 35.8
Available-for-sale investments, Total 144.0 138.5
Available-for-sale investments - non-current | Municipal bonds
   
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale investments maturities 1 to 3 years 109.0 102.7
Available-for-sale investments maturities over 3 years 26.1 23.8
Available-for-sale investments, Total 135.1 126.5
Available-for-sale investments - non-current | Auction rate securities
   
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale investments maturities over 3 years 8.9 12.0
Available-for-sale investments, Total 8.9 12.0
Other non-current investments
   
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale investments maturities less than 1 year 4.0  
Available-for-sale investments, Total 4.0  
Total non-current investments
   
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale investments maturities less than 1 year 4.0  
Available-for-sale investments maturities 1 to 3 years 109.0 102.7
Available-for-sale investments maturities over 3 years 35.0 35.8
Available-for-sale investments, Total $ 148.0 $ 138.5