OPERATING SEGMENT DATA - Operating Expenses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
OPERATING EXPENSES
Salaries, wages, and benefits	$ 1,768,581	$ 1,781,304	$ 1,728,653
Fuel, supplies, and expenses	433,237	479,688	488,009
Depreciation and amortization	149,087	145,349	138,159
Contingent consideration	(90,250)	(19,100)	18,300
Asset impairment charges	1,700	30,162
Other	194,116	194,752	160,698
Gain on sale of subsidiary			(402)
Total consolidated operating expenses	3,934,585	4,254,824	4,634,482
Operating Segments | Asset-Based
OPERATING EXPENSES
Salaries, wages, and benefits	1,387,491	1,379,756	1,293,487
Fuel, supplies, and expenses	316,526	361,355	378,558
Operating taxes and licenses	54,056	55,918	52,290
Insurance	72,610	52,025	47,382
Communications and utilities	19,336	19,288	18,949
Depreciation and amortization	110,021	104,165	97,322
Rents and purchased transportation	274,312	338,575	441,167
Shared services	270,182	279,248	281,698
Asset impairment charges		700
(Gain) loss on sale of property and equipment and asset impairment charges	(803)	982	(12,468)
Innovative technology costs		21,711	27,207
Other	3,800	4,829	4,175
Total consolidated operating expenses	2,507,531	2,617,852	2,629,767
Noncash gain on a like-kind property exchange of a service center			(4,300)
Operating Segments | Asset-Light
OPERATING EXPENSES
Purchased transportation	1,339,783	1,435,604	1,784,668
Salaries, wages, and benefits	118,983	129,083	150,694
Supplies and expenses	10,232	12,094	13,955
Depreciation and amortization	20,062	20,370	20,730
Shared services	68,346	65,308	67,439
Contingent consideration	(90,250)	(19,100)	18,300
Asset impairment charges	1,700	14,407
Legal settlement	274	9,500
Other	25,362	25,650	31,163
Gain on sale of subsidiary			(402)
Total consolidated operating expenses	1,494,492	1,692,916	2,086,547
Other and eliminations
OPERATING EXPENSES
Depreciation and amortization	19,004	20,814	20,107
Asset impairment charges		15,100
Total consolidated operating expenses	$ (67,438)	$ (55,944)	$ (81,832)