Consolidated Statements of Earnings - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating revenues	$ 12,829,665	$ 14,813,999	$ 12,168,302
Operating expenses:
Rents and purchased transportation	5,872,591	7,392,179	6,449,068
Salaries, wages and employee benefits	3,257,484	3,373,063	2,761,680
Fuel and fuel taxes	751,497	931,710	530,642
Depreciation and amortization	737,954	644,520	557,093
Operating supplies and expenses	509,354	502,553	369,294
Insurance and claims	315,678	318,123	165,052
General and administrative expenses, net of asset dispositions	274,564	215,361	195,616
Operating taxes and licenses	74,996	68,230	59,462
Communication and utilities	42,351	36,707	34,865
Total operating expenses	11,836,469	13,482,446	11,122,772
Operating income	993,196	1,331,553	1,045,530
Interest income	7,624	1,069	493
Interest expense	65,933	51,249	46,251
Earnings before income taxes	934,887	1,281,373	999,772
Income taxes	206,600	312,022	238,966
Net earnings	$ 728,287	$ 969,351	$ 760,806
Weighted average basic shares outstanding (in shares)	103,440	104,141	105,359
Basic earnings per share (in dollars per share)	$ 7.04	$ 9.31	$ 7.22
Weighted average diluted shares outstanding (in shares)	104,451	105,276	106,593
Diluted earnings per share (in dollars per share)	$ 6.97	$ 9.21	$ 7.14
Service Excluding Fuel Surcharge [Member]
Operating revenues	$ 10,978,387	$ 12,381,359	$ 10,915,442
Fuel Surcharge [Member]
Operating revenues	$ 1,851,278	$ 2,432,640	$ 1,252,860