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Investments - Additional Information (Detail) (USD $)
Jul. 28, 2012
Jan. 28, 2012
Gain (Loss) on Investments [Line Items]    
Gross Unrealized Losses $ 1,471,000 $ 2,104,000
Cash, cash equivalents and short-term investments 2,100,000,000  
Long-term investments
   
Gain (Loss) on Investments [Line Items]    
Gross Unrealized Losses 1,397,000 1,285,000
Long-term investments | Auction rate securities
   
Gain (Loss) on Investments [Line Items]    
Par value of auction rate securities 19,500,000  
Gross Unrealized Losses $ 1,400,000