Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 27, 2025 USD ($) Segment $ / shares shares	Dec. 28, 2024 USD ($) $ / shares shares	Dec. 30, 2023 USD ($) shares
Significant Accounting Policies [Line Items]
Number of reporting units \| Segment	2
Dividends payable	$ 68,117,000	$ 70,632,000
Agent notes receivable	$ 30,761,000	$ 26,606,000
Weighted average number of shares outstanding, diluted, adjustment \| shares	0	0	0
Common Stock [Member] \| S 2025 A Dividends [Member]
Significant Accounting Policies [Line Items]
Dividends payable per share \| $ / shares	$ 2
Dividend payable date	Jan. 21, 2026
Dividend record date	Jan. 06, 2026
Dividends payable	$ 68,117,000
Dividend announced date	Dec. 04, 2025
Common Stock [Member] \| S 2024 A Dividends [Member]
Significant Accounting Policies [Line Items]
Dividends payable per share \| $ / shares		$ 2
Dividend payable date		Jan. 21, 2025
Dividend record date		Jan. 07, 2025
Dividends payable		$ 70,632,000
Dividend announced date		Dec. 09, 2024
Buildings And Improvements
Significant Accounting Policies [Line Items]
Depreciated life	30 years
Trailing Equipment \| Maximum
Significant Accounting Policies [Line Items]
Depreciated life	10 years
Trailing Equipment \| Minimum
Significant Accounting Policies [Line Items]
Depreciated life	7 years
Hardware And Software \| Maximum
Significant Accounting Policies [Line Items]
Depreciated life	7 years
Hardware And Software \| Minimum
Significant Accounting Policies [Line Items]
Depreciated life	3 years
Commercial Trucking Claims
Significant Accounting Policies [Line Items]
Company retained aggregate liability	$ 10,000,000
Self insurance excess value maintain third party	5,000,000
Commercial Trucking Claims \| Initial Excess Policy [Member]
Significant Accounting Policies [Line Items]
Liability for claims and claims adjustment expense	18,000,000
Commercial Trucking Claims \| Third Party Insurance [Member] \| Excess Coverage Policy [Member]
Significant Accounting Policies [Line Items]
Self insurance excess value maintain third party	10,000,000
Commercial Trucking Claims \| Maximum
Significant Accounting Policies [Line Items]
Company retained liability per claim	10,000,000
Commercial Trucking Claims \| Maximum \| Initial Excess Policy [Member]
Significant Accounting Policies [Line Items]
Company retained aggregate liability			$ 15,000,000
Commercial Trucking Claims \| Minimum
Significant Accounting Policies [Line Items]
Company retained liability per claim	5,000,000
Commercial Trucking Claims \| Minimum \| Initial Excess Policy [Member]
Significant Accounting Policies [Line Items]
Company retained aggregate liability			$ 5,000,000
General Liability Claim
Significant Accounting Policies [Line Items]
Company retained liability per claim	2,000,000
Workers' Compensation Claim
Significant Accounting Policies [Line Items]
Company retained liability per claim	250,000
Workers' Compensation Claim \| BCO Independent Contractor
Significant Accounting Policies [Line Items]
Company retained liability per claim	750,000
Cargo Claim
Significant Accounting Policies [Line Items]
Company retained liability per claim	250,000
Occupational Reinsurance Claims One [Member] \| BCO Independent Contractor
Significant Accounting Policies [Line Items]
Company retained liability per claim	500,000
Occupational Reinsurance Claims Two [Member] \| BCO Independent Contractor
Significant Accounting Policies [Line Items]
Company retained liability per claim	1,000,000
Occupational Reinsurance Claims Three [Member] \| BCO Independent Contractor
Significant Accounting Policies [Line Items]
Company retained liability per claim	$ 2,000,000
Transportation Logistics [Member]
Significant Accounting Policies [Line Items]
Goodwill, Impairment Loss, Statement of Income or Comprehensive Income [Extensible Enumeration]	Asset Impairment Charges
Goodwill, Impairment Loss	$ 7,530,000

LANDSTAR SYSTEM INC 10-K