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Estimate of Fair Value of Option Award using Black-Scholes Option Valuation Model (Detail) (USD $)	9 Months Ended
	Oct. 27, 2012	Oct. 29, 2011
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Dividend yield	2.60%	1.80%
Volatility	33.70%	33.00%
Risk-free interest rate	1.00%	2.10%
Expected life in years	5 years 6 months	5 years 6 months
Weighted average fair value at grant date	$ 11.84	$ 14.60

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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