CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Statement [Abstract]
Operating revenue	$ 4,202,585	$ 5,340,490	$ 4,232,383
Operating expenses:
Purchased transportation and warehousing	3,145,595	4,036,503	3,172,122
Salaries and benefits	553,326	543,010	589,997
Depreciation and amortization	143,523	131,789	116,473
Insurance and claims	49,040	58,064	44,467
General and administrative	105,705	120,579	90,040
Gain on sale of assets, net	(6,835)	(24,176)	(19,173)
Total operating expenses	3,990,354	4,865,769	3,993,926
Operating income	212,231	474,721	238,457
Other income (expense):
Interest expense	(13,435)	(7,506)	(7,307)
Interest income	10,011	874	5
Other, net	397	(131)	(245)
Total other expense, net	(3,027)	(6,763)	(7,547)
Income before provision for income taxes	209,204	467,958	230,910
Provision for income taxes	41,676	111,010	59,436
Net income	167,528	356,948	171,474
Other comprehensive income:
Foreign currency translation adjustments	85	(7)	(16)
Total comprehensive income	$ 167,613	$ 356,941	$ 171,458
Earnings per share net income
Basic earnings per common share	$ 2.65	$ 5.37	$ 2.56
Diluted earnings per common share	$ 2.62	$ 5.32	$ 2.53
Basic weighted average number of shares outstanding	63,324	66,418	66,868
Diluted weighted average number of shares outstanding	63,954	67,118	67,784