Summary of significant accounting policies - Property and Equipment (Details)	12 Months Ended
	Jan. 30, 2021
Equipment and fixtures | Minimum
Property and equipment
Estimated useful lives or the expected lease term	1 year
Equipment and fixtures | Maximum
Property and equipment
Estimated useful lives or the expected lease term	10 years
Electronic equipment and software | Minimum
Property and equipment
Estimated useful lives or the expected lease term	3 years
Electronic equipment and software | Maximum
Property and equipment
Estimated useful lives or the expected lease term	5 years