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Summary of significant accounting policies - Estimated Grant Date Fair Value of Stock Options Weighted-Average Assumptions (Detail)
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9 Months Ended | |
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Oct. 27, 2012
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Oct. 29, 2011
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||
| Volatility rate | 53.40% | 54.00% |
| Average risk-free interest rate | 1.20% | 1.50% |
| Average expected life (in years) | 6.3 | 6.3 |
| Dividend yield | ||
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- Definition
Share-based Compensation Arrangement by Share-based Payment Awards, Fair Value Assumptions, Expected Term No definition available.
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- Definition
The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The risk-free interest rate assumption that is used in valuing an option on its own shares. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The range of expected volatilities used and the weighted-average expected volatility for an entity using a valuation technique with different volatilities during the contractual term. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Details
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