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Fair Value of Each Market-Based Option Award Estimated Using Monte Carlo Simulation Model (Detail) (Market Based Option Award, USD $)
3 Months Ended 6 Months Ended
Jul. 30, 2011
Jul. 30, 2011
Market Based Option Award
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Estimated fair value   $ 5.08
Expected Volatility   42.00%
Risk-free interest rate   0.85%
Risk-free interest rate   3.59%
Dividend yield