Name:	unf_AccrualForEnvironmentalLossContingenciesEffectOfInflation
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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.

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No definition available.

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

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No definition available.

Name:	unf_AccrualForEnvironmentalLossContingenciesUndiscountedDueInThreeYearsNetOfEstimatedInsuranceProceeds
Namespace Prefix:	unf_
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No definition available.

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

Name:	unf_AccrualForEnvironmentalLossContingenciesUndiscountedRemainderOfFiscalYearNetOfEstimatedInsuranceProceeds
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Accrual for Environmental Loss Contingencies, Net of Estimated Insurance Proceeds, Fiscal Year Maturity [Abstract]

No definition available.

Name:	unf_AccrualforEnvironmentalLossContingenciesNetofEstimatedInsuranceProceedsFiscalYearMaturityAbstract
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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
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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 after the fifth year of the balance sheet date.

No definition available.

Name:	unf_EstimatedInsuranceProceedsForEnvironmentalLossContingenciesUndiscountedDueAfterFifthYear
Namespace Prefix:	unf_
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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 five years of the balance sheet date.

No definition available.

Name:	unf_EstimatedInsuranceProceedsForEnvironmentalLossContingenciesUndiscountedDueInFifthYear
Namespace Prefix:	unf_
Data Type:	xbrli:monetaryItemType
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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 four years of the balance sheet date.

No definition available.

Name:	unf_EstimatedInsuranceProceedsForEnvironmentalLossContingenciesUndiscountedDueInFourthYear
Namespace Prefix:	unf_
Data Type:	xbrli:monetaryItemType
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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
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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 three years of the balance sheet date.

No definition available.

Name:	unf_EstimatedInsuranceProceedsForEnvironmentalLossContingenciesUndiscountedDueInThirdYear
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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 the remainder of the fiscal year.

No definition available.

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

No definition available.

Name:	unf_EstimatedInsuranceProceedsforEnvironmentalLossCoontingenciesFiscalYearMaturityAbstract
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Total costs accrued as of the balance sheet date for environmental loss contingencies.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Topic 410
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13207-110859

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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.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section S99
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- References

No definition available.

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Undiscounted amount of the accrual for environmental loss contingencies.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 30
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-URI http://asc.fasb.org/extlink&oid=27011672&loc=d3e149879-122751

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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.

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Undiscounted amount of the accrual for environmental loss contingencies expected to be paid in the remainder of the 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.

No definition available.

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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.

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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.