LONG-TERM DEBT AND FINANCING ARRANGEMENTS - Assets Securing Notes (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Financing Arrangements
Total assets securing notes payable	$ 331,097	$ 339,060
Less accumulated depreciation	154,571	135,305
Net assets securing notes payable	176,526	203,755
Revenue Equipment
Financing Arrangements
Total assets securing notes payable	302,510	300,922
Service, office and other equipment
Financing Arrangements
Total assets securing notes payable	$ 28,587	$ 38,138