Organization and principal accounting policies - Additional information (Details)	3 Months Ended
	May 04, 2019 segment
Property, Plant and Equipment [Line Items]
Number of reportable segments (segment)	3
Minimum
Property, Plant and Equipment [Line Items]
Seasonal revenues, fourth quarter sales, percent	35.00%
Maximum
Property, Plant and Equipment [Line Items]
Seasonal revenues, fourth quarter sales, percent	40.00%