LONG-TERM DEBT AND FINANCING ARRANGEMENTS - Assets Securing Notes (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Financing Arrangements
Total assets securing notes payable	$ 344,722	$ 336,222
Less accumulated depreciation	143,087	119,244
Net assets securing notes payable	201,635	216,978
Revenue equipment
Financing Arrangements
Total assets securing notes payable	305,601	294,700
Service, office, and other equipment
Financing Arrangements
Total assets securing notes payable	$ 39,121	$ 41,522