Information Regarding Reportable Business Segments (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 30, 2017	Sep. 30, 2017	Jul. 01, 2017	Apr. 01, 2017	Dec. 31, 2016	Sep. 24, 2016	Jun. 25, 2016	Mar. 26, 2016	Dec. 30, 2017	Dec. 31, 2016	Dec. 26, 2015
Segment Reporting Information [Line Items]
External revenue	$ 1,051,592	$ 943,430	$ 870,434	$ 780,908	$ 892,829	$ 787,938	$ 775,223	$ 711,644	$ 3,646,364	$ 3,167,634	$ 3,321,091
Internal revenue									37,110	36,118	31,342
Investment income									2,498	1,502	1,396
Interest and debt expense									3,166	3,794	2,949
Depreciation and amortization									40,560	35,796	29,102
Operating income	70,049	$ 60,567	$ 61,018	$ 52,334	63,765	$ 58,461	$ 53,093	$ 47,932	243,968	223,251	241,706
Expenditures on long-lived assets									15,586	22,645	4,804
Goodwill	39,065				31,134				39,065	31,134	31,134
Capital lease additions									33,560	61,504	49,491
Total assets	1,352,460				1,096,591				1,352,460	1,096,591	991,518
Transportation Logistics
Segment Reporting Information [Line Items]
External revenue									3,599,382	3,121,210	3,276,677
Interest and debt expense									3,166	3,794	2,949
Depreciation and amortization									40,560	35,796	29,102
Operating income									209,615	187,813	207,883
Expenditures on long-lived assets									15,586	22,645	4,804
Goodwill	39,065				31,134				39,065	31,134	31,134
Capital lease additions									33,560	61,504	49,491
Total assets	1,132,766				913,667				1,132,766	913,667	842,550
Insurance
Segment Reporting Information [Line Items]
External revenue									46,982	46,424	44,414
Internal revenue									37,110	36,118	31,342
Investment income									2,498	1,502	1,396
Operating income									34,353	35,438	33,823
Total assets	$ 219,694				$ 182,924				$ 219,694	$ 182,924	$ 148,968