Consolidated Statements of Earnings - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating revenues	$ 14,813,999	$ 12,168,302	$ 9,636,573
Operating expenses:
Rents and purchased transportation	7,392,179	6,449,068	4,954,123
Salaries, wages and employee benefits	3,373,063	2,761,680	2,347,716
Fuel and fuel taxes	931,710	530,642	357,483
Depreciation and amortization	644,520	557,093	527,375
Operating supplies and expenses	502,553	369,294	334,350
Insurance and claims	318,123	165,052	134,482
General and administrative expenses, net of asset dispositions	215,361	195,616	180,083
Operating taxes and licenses	68,230	59,462	54,331
Communication and utilities	36,707	34,865	33,511
Total operating expenses	13,482,446	11,122,772	8,923,454
Operating income	1,331,553	1,045,530	713,119
Interest income	1,069	493	486
Interest expense	51,249	46,251	47,580
Earnings before income taxes	1,281,373	999,772	666,025
Income taxes	312,022	238,966	159,990
Net earnings	$ 969,351	$ 760,806	$ 506,035
Weighted average basic shares outstanding (in shares)	104,141	105,359	105,700
Basic earnings per share (in dollars per share)	$ 9.31	$ 7.22	$ 4.79
Weighted average diluted shares outstanding (in shares)	105,276	106,593	106,766
Diluted earnings per share (in dollars per share)	$ 9.21	$ 7.14	$ 4.74
Service Excluding Fuel Surcharge [Member]
Operating revenues	$ 12,381,359	$ 10,915,442	$ 8,879,653
Fuel Surcharge [Member]
Operating revenues	$ 2,432,640	$ 1,252,860	$ 756,920