Summary of Significant Accounting Policies (Revenue Recognition) (Details)	12 Months Ended
Feb. 02, 2019
Accounting Policies [Abstract]
Period of sales return acceptance	14 days

Revenue Recognition, Sales Returns, Period of Returns

No definition available.

Name:	five_RevenueRecognitionSalesReturnsPeriodofReturns
Namespace Prefix:	five_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration