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Significant Accounting Policies (Schedule of Weighted Average Assumptions for Share-based Awards Granted) (Detail)	0 Months Ended	6 Months Ended	12 Months Ended
	Jul. 25, 2012	Jan. 26, 2012	Jul. 27, 2011
Accounting Policies [Abstract]
Expected dividend yield	0.00%	0.00%	0.00%
Risk - free interest rate	0.46%	0.52%	1.16%
Expected volatility	66.50%	64.90%	65.50%
Expected life	4 years	4 years	4 years

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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