Asset Retirement Obligations (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Aug. 27, 2011	Aug. 28, 2010	Aug. 29, 2009
Asset Retirement Obligations [Abstract]
Estimated impact of inflation per year (in hundredths)	3.00%
Credit-adjusted risk-free rates, minimum (in hundredths)	7.00%
Credit-adjusted risk-free rates, maximum (in hundredths)	7.50%
Range of years discount for estimated future costs to decommission its nuclear laundry facilities, minimum years (in years)	1Y
Range of years discount for estimated future costs to decommission its nuclear laundry facilities, maximum years (in years)	33Y
Rollforward of asset retirement liabilities [Abstract]
Beginning balance	$ 8,899	$ 8,584
Accretion expense	589	568	517
Revisions in estimates	0	(253)
Ending balance	$ 9,488	$ 8,899	$ 8,584

This element represents the maximum rate that a liability is discounted, using a credit-adjusted risk-free rate. Credit-adjusting the risk-free rate means adding to the Treasury rates some amount of additional interest-rate basis points to reflect the fact that companies might default on their debt obligations.

Name:	unf_CreditAdjustedRiskFreeRatesMaximumRate
Namespace Prefix:	unf
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the minimum rate that a liability is discounted, using a credit-adjusted risk-free rate. Credit-adjusting the risk-free rate means adding to the Treasury rates some amount of additional interest-rate basis points to reflect the fact that companies might default on their debt obligations.

+ Details

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Namespace Prefix:	unf
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the percentage added to estimated current cost of decommissioning one of the Company's facilities based on future estimated inflation rate.

+ Details

Name:	unf_EstimatedImpactOfInflationPerYear
Namespace Prefix:	unf
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

This element describes the maximum years the Company will discount the liability of estimated future costs to decommission one of its facilities.

+ Details

Name:	unf_RangeOfYearsDiscountForEstimatedFutureCostsToDecommissionItsNuclearLaundryFacilitiesMaximumYears
Namespace Prefix:	unf
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	duration

- Definition

This element describes the minimum years the Company will discount the liability of estimated future costs to decommission one of its facilities.

+ Details

Name:	unf_RangeOfYearsDiscountForEstimatedFutureCostsToDecommissionItsNuclearLaundryFacilitiesMinimumYears
Namespace Prefix:	unf
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	duration

- Definition

The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 143

-Paragraph 3, 10, 22

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 410

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Asset Retirement Obligation

-URI http://asc.fasb.org/extlink&oid=6505190

+ Details

Name:	us-gaap_AssetRetirementObligation
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_AssetRetirementObligationAbstract
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- Definition

Amount of accretion expense recognized during the period that is associated with an asset retirement obligation. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 410

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (c)(3)

-URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 143

-Paragraph 13, 14

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 143

-Paragraph 22

-Subparagraph c(3)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 410

-SubTopic 20

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6392676&loc=d3e7480-110848

+ Details

Name:	us-gaap_AssetRetirementObligationAccretionExpense
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of the Increase or Decrease in the amount of the asset retirement obligation during the current period for changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 143

-Paragraph 22

-Subparagraph c(4)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 410

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (c)(4)

-URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ Details

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