OPERATING SEGMENT DATA - Operating Expenses by Category (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
OPERATING EXPENSES
Salaries, wages, and benefits	$ 456,022	$ 444,164	$ 1,342,028	$ 1,301,944
Rents, purchased transportation, and other costs of services	410,436	517,106	1,255,753	1,633,193
Fuel, supplies, and expenses	122,700	125,349	369,466	365,213
Depreciation and amortization	37,141	34,229	107,962	103,509
Contingent consideration	(17,840)		(12,800)	810
Lease impairment charges	30,162		30,162
Other	44,638	39,546	136,971	116,527
Total consolidated operating expenses	$ 1,083,259	$ 1,160,394	$ 3,229,542	$ 3,521,196