SEGMENT REPORTING - Segment Reporting Information by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information
Operating revenue	$ 170,031	$ 123,737	$ 328,536	$ 250,510
Operating income	6,929	1,000	12,975	(1,312)
Depreciation and amortization	9,163	10,034	18,733	20,045
Trucking
Segment Reporting Information
Operating revenue	105,102	87,920	207,878	180,921
USAT Logistics
Segment Reporting Information
Operating revenue	64,929	35,817	120,658	69,589
Operating Segments
Segment Reporting Information
Operating revenue			328,536	250,510
Operating Segments | Trucking
Segment Reporting Information
Operating revenue	105,361	88,627	208,464	182,622
Operating income	3,057	1,176	6,577	(511)
Depreciation and amortization	8,901	9,697	18,197	19,473
Operating Segments | USAT Logistics
Segment Reporting Information
Operating revenue	78,749	38,738	147,130	74,562
Operating income	3,872	(176)	6,398	(801)
Depreciation and amortization	262	337	536	572
Intersegment Eliminations
Segment Reporting Information
Operating revenue	(14,079)	(3,628)	(27,058)	(6,674)
Intersegment Eliminations | Trucking
Segment Reporting Information
Operating revenue	(259)	(707)	(586)	(1,701)
Intersegment Eliminations | USAT Logistics
Segment Reporting Information
Operating revenue	(13,820)	(2,921)	(26,472)	(4,973)
Foreign Countries | Operating Segments | Trucking
Segment Reporting Information
Operating revenue	$ 10,000	$ 7,500	$ 18,900	$ 16,100