Condensed Consolidated Statements of Operations and Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenues:
Total revenues	$ 6,263,695	$ 4,224,800	$ 16,600,290	$ 11,657,654
Costs and expenses:
Personnel expenses	399,880	302,904	1,123,616	933,607
Other selling, general, and administrative expenses	133,543	118,130	377,430	371,606
Total costs and expenses	5,952,926	4,056,561	15,805,588	11,191,188
Income from operations	310,769	168,239	794,702	466,466
Interest and other expense	(16,662)	(7,465)	(41,419)	(32,904)
Income before provision for income taxes	294,107	160,774	753,283	433,562
Provision for income taxes	47,054	24,245	139,136	74,948
Net income	247,053	136,529	614,147	358,614
Other comprehensive (loss) income, net of tax	(12,034)	13,236	(19,482)	5,294
Comprehensive income	$ 235,019	$ 149,765	$ 594,665	$ 363,908
Basic net income per share (in dollars per share)	$ 1.87	$ 1.01	$ 4.61	$ 2.65
Diluted net income per share (in dollars per share)	$ 1.85	$ 1.00	$ 4.56	$ 2.63
Basic weighted average shares outstanding (shares)	131,845	135,671	133,201	135,385
Dilutive effect of outstanding stock awards (shares)	1,591	1,457	1,460	752
Diluted weighted average shares outstanding (shares)	133,436	137,128	134,661	136,137
Transportation
Revenues:
Total revenues	$ 5,999,901	$ 3,944,981	$ 15,800,576	$ 10,835,710
Costs and expenses:
Purchased products and services	5,180,390	3,378,651	13,580,980	9,141,354
Sourcing
Revenues:
Total revenues	263,794	279,819	799,714	821,944
Costs and expenses:
Purchased products and services	$ 239,113	$ 256,876	$ 723,562	$ 744,621