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v3.19.3.a.u2

Asset Retirement Obligations - Narrative (Details) | 3 Months Ended
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Nov. 30, 2019
Minimum |
Asset Retirement Obligations [Line Items] |
Remaining lives | 1 year
Maximum |
Asset Retirement Obligations [Line Items] |
Remaining lives | 24 years

X
- Definition This element describes the minimum years the Company will discount the liability of estimated future costs to decommission one of its facilities. + References No definition available. + Details
Name: | unf_AssetRetirementObligationRemainingLives
Namespace Prefix: | unf_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition [Line Items] for Asset Retirement Obligations [Table] + References No definition available. + Details
Name: | unf_AssetRetirementObligationsLineItems
Namespace Prefix: | unf_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |