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Summary of Significant Accounting Policies (Cash and Cash Equivalents) (Details) - USD ($) $ in Millions	12 Months Ended
	Feb. 03, 2018	Jan. 28, 2017
Significant Accounting Policies [Line Items]
Cash Equivalents	$ 91.2	$ 36.3
Cash and Cash Equivalents [Member]
Significant Accounting Policies [Line Items]
Cash Equivalents	$ 6.0	$ 4.3
Minimum [Member]
Significant Accounting Policies [Line Items]
Debit and credit card transaction processing period (hours)	24 hours
Maximum [Member]
Significant Accounting Policies [Line Items]
Debit and credit card transaction processing period (hours)	48 hours

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- Definition

Cash Equivalents

+ References

No definition available.

+ Details

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Namespace Prefix:	five_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Debit and Credit Card Transaction Processing Period

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No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

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- Definition

Significant Accounting Policies [Line Items]

+ References

No definition available.

+ Details

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Period Type:	duration

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- Details

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Namespace Prefix:
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Balance Type:
Period Type:

X

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

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