Additional commitment in line of credit facility maximum borrowing capacity.

No definition available.

Name:	unf_AdditionalCommitmentInLineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	unf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line of credit facility increase the aggregate commitment.

+ References

No definition available.

+ Details

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Namespace Prefix:	unf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Maximum additional amount of line of credit facility increase the aggregate commitment.

+ References

No definition available.

+ Details

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Namespace Prefix:	unf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Date when the debt instrument is scheduled to be fully repaid, in YYYY-MM-DD format.

+ References

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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

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+ Details

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum amount borrowed under the credit facility at any time during the period.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-SubTopic 10
-Section S99
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-Subparagraph (SX 210.5-02.19(b),22(b))
-Publisher FASB
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	credit
Period Type:	instant

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Balance Type:
Period Type:

- Details

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Period Type:

- Details

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Balance Type:
Period Type:

- Details

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Period Type:

Long-Term Debt - Narrative (Details) - USD ($) $ in Millions			3 Months Ended	12 Months Ended
	Mar. 09, 2023	Mar. 26, 2021	May 27, 2023	Aug. 26, 2023	Aug. 27, 2022
Debt Instrument [Line Items]
Outstanding letters of credit				$ 66.5	$ 60.8
Revolving Credit Facility \| Credit Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 275.0	$ 175.0
Additional commitments amount in maximum borrowing capacity	375.0
Maturity date		Mar. 26, 2026
Outstanding borrowings				0.0
Outstanding letters of credit				66.5
Amount available for borrowing				$ 208.5
Increases in aggregate commitments	100.0
Maximum additional amount increases in aggregate commitments	$ 100.0
Revolving Credit Facility \| Credit Agreement \| Clean Holdco, Inc.
Debt Instrument [Line Items]
Maximum amount borrowed			$ 80.0
Revolving Credit Facility \| Credit Agreement \| SOFR
Debt Instrument [Line Items]
Basis spread on variable rate (as percent)				1.00%