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Employee Benefit Plans - Narrative (Details) - USD ($) $ in Millions | 12 Months Ended
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Aug. 31, 2024 | Aug. 26, 2023 | Aug. 27, 2022
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Contributions charged to expense under the plan | $ 20.3 | $ 18.7 | $ 18.2
SERP |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Amounts charged to expense related to the plan | 1.7 | 1.7 | 1.5
Accumulated benefit obligations | 23.4 | 22.5 |
UniFirst Plan |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Amounts charged to expense related to the plan | 0.2 | 0.1 | $ 0.1
Accumulated benefit obligations | 3.6 | 3.5 |
Non-qualified Deferred Compensation Plan |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Amounts charged to expense related to the plan | 0.8 | 0.3 |
NQDC Plan assets | 3.3 | 2.0 |
NQDC Plan liabilities, current | $ 1.6 | $ 0.5 |

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- Definition Carrying amount as of the balance sheet date of assets held under deferred compensation agreements. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(17)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1 + Details
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- Definition Amount of actuarial present value of benefits attributed to employee service rendered, excluding assumptions about future compensation level. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (e) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition Amount of cost for defined contribution plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 70 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480794/715-70-50-1 + Details
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