Commitments and Contingencies - Additional Information (Detail)	12 Months Ended
	Dec. 29, 2018 USD ($)
Commitments and Contingencies Disclosure [Line Items]
Consideration paid to purchase remaining equity interest	$ 600,000
Fletes Avella | Landstar Metro
Commitments and Contingencies Disclosure [Line Items]
Approximate ownership interest acquired by affiliates	21.00%
Fletes Avella | Landstar Servicios
Commitments and Contingencies Disclosure [Line Items]
Approximate ownership interest acquired by affiliates	21.00%
Revolving Credit Facility
Commitments and Contingencies Disclosure [Line Items]
Letters of credit outstanding	$ 62,345,000
Guarantee Payment of Insurance Claims
Commitments and Contingencies Disclosure [Line Items]
Letters of credit outstanding	$ 62,345,000