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Summary of significant accounting policies - Additional Information (Detail) (USD $)
In Thousands, except Per Share data, unless otherwise specified |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
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Aug. 03, 2013
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Jul. 28, 2012
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Aug. 03, 2013
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Jul. 28, 2012
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||
| Stock compensation expenses | $ 7,539 | $ 6,346 | ||
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Stock Options [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||
| Number of shares granted | 267 | 183 | ||
| Weighted average fair value of stock option | $ 40.52 | $ 45.00 | ||
| Stock compensation expenses | 3,322 | 3,076 | 5,637 | 5,862 |
| Unrecognized compensation expense related to unvested stock awards | 26,875 | 26,875 | ||
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Restricted Stock [Member]
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||
| Number of shares granted | 120 | 46 | ||
| Stock compensation expenses | 1,169 | 377 | 1,902 | 484 |
| Unrecognized compensation expense related to unvested stock awards | $ 11,373 | $ 11,373 | ||