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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 | |
|---|---|---|
|
May 03, 2014
|
May 04, 2013
|
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||
| Compensation expenses | $ 4,063 | $ 3,048 |
|
Employee Stock Option [Member]
|
||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||
| Number of shares granted | 287 | 207 |
| Weighted average fair value of stock option | $ 32.04 | $ 38.29 |
| Compensation expenses | 2,133 | 2,315 |
| Unrecognized compensation expense | 23,157 | |
|
Restricted Stock [Member]
|
||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||
| Number of shares granted | 46 | 89 |
| Compensation expenses | 1,930 | 733 |
| Unrecognized compensation expense | $ 10,957 | |