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Valuation Assumptions for Stock Options and Restricted Stock (Detail)	9 Months Ended
	Oct. 27, 2012	Oct. 29, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	55.00%	55.00%
Risk-free interest rate, minimum	0.31%	0.32%
Risk-free interest rate, maximum	0.67%	1.89%
Dividend rate
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life	3 years	2 years 6 months
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life	4 years 6 months	4 years 6 months

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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