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Held for Sale Subsidiary - Additional Information (Detail) - Landstar Metro [Member] | 9 Months Ended
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Sep. 27, 2025 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |
Goodwill, Impairment Loss | $ 7,530,000
Impairment of Long-Lived Assets to be Disposed of | $ 8,612,000

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