Annual report pursuant to Section 13 and 15(d)

Summary of significant accounting policies - Fiscal Year (Details)

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Summary of significant accounting policies - Fiscal Year (Details)
 3 Months Ended 12 Months Ended
Feb. 03, 2018
Oct. 28, 2017
Jul. 29, 2017
Apr. 29, 2017
Jan. 28, 2017
Oct. 29, 2016
Jul. 30, 2016
Apr. 30, 2016
Feb. 03, 2018
Jan. 28, 2017
Jan. 30, 2016
Summary of significant accounting policies                      
Fiscal period 98 days 91 days 91 days 91 days 91 days 91 days 91 days 91 days 371 days 364 days 364 days
Minimum                      
Summary of significant accounting policies                      
Fiscal period                 364 days    
Maximum                      
Summary of significant accounting policies                      
Fiscal period                 371 days