v2.4.0.6
Summary of Financial Assets Measured at Fair Value on Recurring Basis (Detail) (USD $)
In Millions, unless otherwise specified
Jan. 28, 2012
Jul. 30, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Financial assets carried at fair value $ 192.0 $ 191.2
Municipal bonds | Level 1
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Financial assets carried at fair value 183.1 [1] 179.2 [1]
Auction rate securities | Level 3
   
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Financial assets carried at fair value $ 8.9 [2] $ 12.0 [2]
[1] Based on Level 1 measurements.
[2] Based on Level 3 measurements.