Condensed Consolidated Statements of Earnings (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating revenues	$ 2,944,001	$ 3,229,588
Operating expenses:
Rents and purchased transportation	1,280,987	1,467,798
Salaries, wages and employee benefits	807,884	824,999
Depreciation and amortization	182,996	175,812
Fuel and fuel taxes	173,527	195,834
Operating supplies and expenses	122,991	128,360
General and administrative expenses, net of asset dispositions	76,784	60,404
Insurance and claims	75,686	70,328
Operating taxes and licenses	17,535	18,108
Communication and utilities	11,242	10,456
Total operating expenses	2,749,632	2,952,099
Operating income	194,369	277,489
Net interest expense	15,649	14,789
Earnings before income taxes	178,720	262,700
Income taxes	51,227	64,932
Net earnings	$ 127,493	$ 197,768
Weighted average basic shares outstanding (in shares)	103,242	103,724
Basic earnings per share (in dollars per share)	$ 1.23	$ 1.91
Weighted average diluted shares outstanding (in shares)	104,107	104,729
Diluted earnings per share (in dollars per share)	$ 1.22	$ 1.89
Service Excluding Fuel Surcharge [Member]
Operating revenues	$ 2,552,486	$ 2,731,453
Fuel Surcharge [Member]
Operating revenues	$ 391,515	$ 498,135