Assumptions used to Compute Share-Based Compensation Expense (Detail) (USD $)	3 Months Ended
Apr. 28, 2012 Year	Apr. 30, 2011 Year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average fair value	$ 30.92
Stock Option Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average risk free rate of interest	1.50%	2.11%
Expected volatility	43.00%	45.00%
Weighted-average expected award life (in years)	5.5	5.0
Dividend yield	2.30%	3.50%
Weighted-average fair value	$ 10.14	$ 5.76
Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average risk free rate of interest	0.21%	0.41%
Expected volatility	35.00%	38.00%
Weighted-average expected award life (in years)	1.0	1.0
Dividend yield	2.70%	4.10%
Weighted-average fair value	$ 4.90	$ 2.96

The period of time an equity-based award is expected to be outstanding. An equity-based award's expected term is generally determined based on, among other factors, the instrument's contractual term and the effects of employees' expected exercise and post-vesting employment termination behavior.

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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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