Investments - Par Value (Detail) (USD $)
In Thousands, unless otherwise specified
3 Months Ended
Apr. 28, 2012
Jan. 28, 2012
Investment Holdings [Line Items]    
Amortized Cost or Par Value $ 17,950 $ 17,975
Auction-rate securities [Member]
   
Investment Holdings [Line Items]    
Amortized Cost or Par Value 15,950 15,975
Auction-rate securities [Member] | Municipal Revenue Bonds [Member]
   
Investment Holdings [Line Items]    
Underlying Collateral 100% insured by AAA/AA/A-rated bond insurers at April 28, 2012  
Amortized Cost or Par Value 10,100  
Auction-rate securities [Member] | Municipal Bond Funds [Member]
   
Investment Holdings [Line Items]    
Underlying Collateral Fixed income instruments within issuers' money market funds  
Amortized Cost or Par Value 2,900  
Auction-rate securities [Member] | Student Loan Bonds [Member]
   
Investment Holdings [Line Items]    
Underlying Collateral Student loans guaranteed by state entities  
Amortized Cost or Par Value 2,950  
Preferred stock [Member]
   
Investment Holdings [Line Items]    
Underlying Collateral Underlying investments of closed-end funds  
Amortized Cost or Par Value $ 2,000 $ 2,000