Segment information - Additional Information (Details)	9 Months Ended
Oct. 28, 2017 state segment province
Segment Reporting [Abstract]
Number of reportable segments \| segment	5
Number of states in which entity operates \| state	50
Number of provinces in which entity operates \| province	9

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

No definition available.

Name:	us-gaap_NumberOfReportableSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration