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Estimated Fair Value of Options (Detail)	12 Months Ended
Estimated Fair Value of Options (Detail)	Jan. 29, 2012	Jan. 30, 2011	Jan. 31, 2010
Assumptions used to Determine Fair Value Options [Line Items]
Risk-free interest rate	2.80%	3.00%	2.90%
Dividend yield	0.00%	0.00%	0.00%
Expected volatility factor	46.00%	48.90%	50.50%
Expected option life in years	6 years 7 months 6 days	6 years 9 months 18 days	7 years 3 months 18 days

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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