Revenue Recognition - Narrative (Details)	3 Months Ended	9 Months Ended
May 31, 2025	May 25, 2024	May 31, 2025	May 25, 2024
Revenue from Contract with Customer [Abstract]
Percentage of revenues derived from route servicing fees	83.90%	83.80%	83.80%	84.10%

Revenue From Contracts With Customers, Percentage Of Revenues From Route Servicing Fees

No definition available.

Name:	unf_RevenueFromContractsWithCustomersPercentageOfRevenuesFromRouteServicingFees
Namespace Prefix:	unf_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration