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Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 30, 2017 | Dec. 31, 2016 | Dec. 26, 2015
Income Taxes [Line Items] |  |  |  |
Federal income tax rate |  | 35.00% |  |
Tax cuts and jobs act of 2017 incomplete accounting revaluation deferred tax liabilities provisional income tax expense (benefit) |  | $ 20,430 |  |
Tax cuts and jobs act of 2017 incomplete accounting deemed repatriation foreign earnings and profits provisional income tax expense (benefit) |  | 17,981 |  |
Tax cuts and jobs act of 2017, incomplete accounting, provisional income tax expense (benefit) |  | 900 |  |
Tax cuts and jobs act of 2017 incomplete accounting deemed repatriation US federal taxes payable |  | $ 500 |  |
Tax cuts and jobs act of 2017 incomplete accounting deemed repatriation US federal taxes payable period |  | 8 years |  |
Net unrecognized tax benefits |  | $ 3,670 | $ 1,829 |
Accrued for estimated interest and penalties |  | 627 | 547 |
Income taxes paid |  | $ 86,607 | $ 69,067 | $ 74,619
Scenario, Forecast |  |  |  |
Income Taxes [Line Items] |  |  |  |
Federal income tax rate | 21.00% |  |  |
Landstar Metro |  |  |  |
Income Taxes [Line Items] |  |  |  |
Ownership in subsidiaries, percentage |  | 70.00% |  |
Landstar Servicios |  |  |  |
Income Taxes [Line Items] |  |  |  |
Ownership in subsidiaries, percentage |  | 70.00% |  |
Accounting Standards Update 2016-09 |  |  |  |
Income Taxes [Line Items] |  |  |  |
Excess tax benefit from stock-based awards |  | $ 1,299 |  |

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