| Summary of significant accounting policies (Tables) | 12 Months Ended | ||||||||||||||||||||
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| Jan. 30, 2016 | |||||||||||||||||||||
| Accounting Policies [Abstract] | |||||||||||||||||||||
| Summary of Estimated Useful Lives or Expected Lease Term | The Company’s assets are depreciated or amortized using the straight-line method, over the shorter of their estimated useful lives or the expected lease term as follows: 
 
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| X | ||||||||||
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- Definition Estimated useful lives or the expected lease term. No definition available. 
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| X | ||||||||||
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- References No definition available. 
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