Name:	unf_AccrualForEnvironmentalLossContingenciesEffectOfInflation
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Data Type:	xbrli:monetaryItemType
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Accrual for environmental loss contingencies, net of estimated insurance proceeds, total.

No definition available.

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Namespace Prefix:	unf_
Data Type:	xbrli:monetaryItemType
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The portion of the estimated aggregate undiscounted amount of the accrual for environmental loss contingencies that is expected to be paid, net of estimated insurance proceeds expected to be received, after the fifth year of the balance sheet date.

No definition available.

Name:	unf_AccrualForEnvironmentalLossContingenciesUndiscountedDueAfterFifthYearNetOfEstimatedInsuranceProceeds
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Data Type:	xbrli:monetaryItemType
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No definition available.

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

No definition available.

Name:	unf_AccrualForEnvironmentalLossContingenciesUndiscountedDueInFourYearsNetOfEstimatedInsuranceProceeds
Namespace Prefix:	unf_
Data Type:	xbrli:monetaryItemType
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No definition available.

Name:	unf_AccrualForEnvironmentalLossContingenciesUndiscountedDueInThreeYearsNetOfEstimatedInsuranceProceeds
Namespace Prefix:	unf_
Data Type:	xbrli:monetaryItemType
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No definition available.

Name:	unf_AccrualForEnvironmentalLossContingenciesUndiscountedDueInTwoYearsNetOfEstimatedInsuranceProceeds
Namespace Prefix:	unf_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

No definition available.

Name:	unf_AccrualForEnvironmentalLossContingenciesUndiscountedDueWithinOneYearNetOfEstimatedInsuranceProceeds
Namespace Prefix:	unf_
Data Type:	xbrli:monetaryItemType
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Accrual for Environmental Loss Contingencies, Net of Estimated Insurance Proceeds, Fiscal Year Maturity [Abstract]

No definition available.

Name:	unf_AccrualforEnvironmentalLossContingenciesNetofEstimatedInsuranceProceedsFiscalYearMaturityAbstract
Namespace Prefix:	unf_
Data Type:	xbrli:stringItemType
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The estimated aggregate undiscounted amount of the estimated insurance proceeds accrual for environmental loss contingencies as of the balance sheet date.

No definition available.

Name:	unf_EstimatedInsuranceProceedsForEnvironmentalLossContingenciesGross
Namespace Prefix:	unf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The portion of the estimated aggregate undiscounted amount of the insurance proceeds for environmental loss contingencies that is expected to be received after the fifth year of the balance sheet date.

No definition available.

Name:	unf_EstimatedInsuranceProceedsForEnvironmentalLossContingenciesUndiscountedDueAfterFifthYear
Namespace Prefix:	unf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The portion of the estimated aggregate undiscounted amount of the insurance proceeds for environmental loss contingencies that is expected to be received within five years of the balance sheet date.

No definition available.

Name:	unf_EstimatedInsuranceProceedsForEnvironmentalLossContingenciesUndiscountedDueInFifthYear
Namespace Prefix:	unf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The portion of the estimated aggregate undiscounted amount of the insurance proceeds for environmental loss contingencies that is expected to be received within four years of the balance sheet date.

No definition available.

Name:	unf_EstimatedInsuranceProceedsForEnvironmentalLossContingenciesUndiscountedDueInFourthYear
Namespace Prefix:	unf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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The portion of the estimated aggregate undiscounted amount of the insurance proceeds for environmental loss contingencies that is expected to be received within two years of the balance sheet date.

No definition available.

Name:	unf_EstimatedInsuranceProceedsForEnvironmentalLossContingenciesUndiscountedDueInSecondYear
Namespace Prefix:	unf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The portion of the estimated aggregate undiscounted amount of the insurance proceeds for environmental loss contingencies that is expected to be received within three years of the balance sheet date.

No definition available.

Name:	unf_EstimatedInsuranceProceedsForEnvironmentalLossContingenciesUndiscountedDueInThirdYear
Namespace Prefix:	unf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The portion of the estimated aggregate undiscounted amount of the insurance proceeds for environmental loss contingencies that is expected to be received within one year of the balance sheet date.

No definition available.

Name:	unf_EstimatedInsuranceProceedsForEnvironmentalLossContingenciesUndiscountedDueWithinOneYear
Namespace Prefix:	unf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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Estimated Insurance Proceeds for Environmental Loss Coontingencies, Fiscal Year Maturity [Abstract]

No definition available.

Name:	unf_EstimatedInsuranceProceedsforEnvironmentalLossCoontingenciesFiscalYearMaturityAbstract
Namespace Prefix:	unf_
Data Type:	xbrli:stringItemType
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Total costs accrued as of the balance sheet date for environmental loss contingencies.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14326-108349

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 30
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13207-110859

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 25
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6395460&loc=d3e13647-108346

Name:	us-gaap_AccrualForEnvironmentalLossContingencies
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Amount of imputed interest necessary to reduce (reconcile) the undiscounted amount of the accrual for environmental loss contingencies to the present value.

Name:	us-gaap_AccrualForEnvironmentalLossContingenciesDiscount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

- References

No definition available.

Name:	us-gaap_AccrualForEnvironmentalLossContingenciesFiscalYearMaturityAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
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Undiscounted amount of the accrual for environmental loss contingencies.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 5.Y.Q1)
-URI http://asc.fasb.org/extlink&oid=27011672&loc=d3e149879-122751

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 30
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13207-110859

Name:	us-gaap_AccrualForEnvironmentalLossContingenciesGross
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Undiscounted amount of the accrual for environmental loss contingencies expected to be paid after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Undiscounted amount of the accrual for environmental loss contingencies expected to be paid in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Undiscounted amount of the accrual for environmental loss contingencies expected to be paid in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

Name:	us-gaap_AccrualForEnvironmentalLossContingenciesUndiscountedDueInFourthYear
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Undiscounted amount of the accrual for environmental loss contingencies expected to be paid in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

Name:	us-gaap_AccrualForEnvironmentalLossContingenciesUndiscountedDueInSecondYear
Namespace Prefix:	us-gaap_
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Undiscounted amount of the accrual for environmental loss contingencies expected to be paid in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

Name:	us-gaap_AccrualForEnvironmentalLossContingenciesUndiscountedDueInThirdYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Undiscounted amount of the accrual for environmental loss contingencies expected to be paid in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.