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Acquired Business and Noncontrolling Interests - Additional Information (Detail) - USD ($) |  | 12 Months Ended |  |
--- | --- | --- | --- | ---
Sep. 20, 2017 | Dec. 30, 2017 | Dec. 31, 2016 | Dec. 26, 2015
Goodwill |  | $ 39,065,000 | $ 31,134,000 | $ 31,134,000
Fletes Avella | Landstar Metro |  |  |  |
Payments to acquire businesses, gross | $ 8,460,000 |  |  |
Business combination, recognized identifiable assets acquired and liabilities assumed, liabilities |  | 1,900,000 |  |
Ownership interest acquired by affiliates | 30.00% |  |  |
Goodwill |  | $ 8,800,000 |  |
Percentage of goodwill estimated to be deductible for tax purposes |  | 70.00% |  |
Percentage of goodwill estimated to be deductible after purchase of noncontrolling interests by the company |  | 100.00% |  |
One-time costs related to completion of acquisition |  | $ 1,000,000 |  |
One-time costs related to completion of acquisition, per share |  | $ 0.01 |  |
One-time costs related to completion of acquisition, per share diluted |  | $ 0.01 |  |
Fletes Avella | Landstar Servicios |  |  |  |
Ownership interest acquired by affiliates | 30.00% |  |  |

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- Definition Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=77989000&loc=SL49117168-202975 + Details
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