Information Regarding Reportable Business Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 26, 2021	Jun. 27, 2020	Jun. 26, 2021	Jun. 27, 2020	Dec. 26, 2020
Segment Reporting Information [Line Items]
External revenue	$ 1,570,718	$ 823,514	$ 2,858,252	$ 1,751,080
Internal revenue	33,961	26,755	43,495	35,834
Investment income	748	835	1,432	2,002
Operating income	122,248	32,181	225,516	86,186
Expenditures on long-lived assets	4,924	11,877	9,000	17,676
Goodwill	40,973	40,071	40,973	40,071	$ 40,949
Transportation Logistics
Segment Reporting Information [Line Items]
External revenue	1,553,058	809,798	2,823,557	1,723,682
Operating income	110,228	21,474	199,960	76,518
Expenditures on long-lived assets	4,924	11,877	9,000	17,676
Goodwill	40,973	40,071	40,973	40,071
Insurance
Segment Reporting Information [Line Items]
External revenue	17,660	13,716	34,695	27,398
Internal revenue	33,961	26,755	43,495	35,834
Investment income	748	835	1,432	2,002
Operating income	$ 12,020	$ 10,707	$ 25,556	$ 9,668