Quarterly report pursuant to Section 13 or 15(d)

Commitments and contingencies - Additional Information (Detail)

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Commitments and contingencies - Additional Information (Detail) (USD $)
In Thousands, unless otherwise specified
3 Months Ended 9 Months Ended
Oct. 27, 2012
Oct. 29, 2011
Oct. 27, 2012
Oct. 29, 2011
Commitment And Contingencies [Line Items]        
Non-cancelable operating lease terms, minimum     3 years  
Non-cancelable operating lease terms, maximum     10 years  
Total rent expense under operating leases $ 29,708 $ 24,713 $ 83,415 $ 69,697