DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue
Operating revenue	$ 710,387	$ 551,138
Freight
Disaggregation of Revenue
Operating revenue	627,047	493,889
Fuel Surcharge
Disaggregation of Revenue
Operating revenue	69,183	45,418
Accessorial
Disaggregation of Revenue
Operating revenue	14,157	11,831
Trucking
Disaggregation of Revenue
Operating revenue	440,346	381,589
USAT Logistics
Disaggregation of Revenue
Operating revenue	270,041	169,549
Operating Segments | Trucking
Disaggregation of Revenue
Operating revenue	441,116	384,256
Operating Segments | Trucking | Freight
Disaggregation of Revenue
Operating revenue	383,331	341,522
Operating Segments | Trucking | Fuel Surcharge
Disaggregation of Revenue
Operating revenue	48,038	35,049
Operating Segments | Trucking | Accessorial
Disaggregation of Revenue
Operating revenue	9,747	7,685
Operating Segments | USAT Logistics
Disaggregation of Revenue
Operating revenue	323,356	191,951
Operating Segments | USAT Logistics | Freight
Disaggregation of Revenue
Operating revenue	296,374	176,439
Operating Segments | USAT Logistics | Fuel Surcharge
Disaggregation of Revenue
Operating revenue	22,572	11,366
Operating Segments | USAT Logistics | Accessorial
Disaggregation of Revenue
Operating revenue	4,410	4,146
Intersegment Eliminations
Disaggregation of Revenue
Operating revenue	(54,085)	(25,069)
Intersegment Eliminations | Freight
Disaggregation of Revenue
Operating revenue	(52,658)	(24,072)
Intersegment Eliminations | Fuel Surcharge
Disaggregation of Revenue
Operating revenue	(1,427)	(997)
Intersegment Eliminations | Trucking
Disaggregation of Revenue
Operating revenue	(770)	(2,667)
Intersegment Eliminations | USAT Logistics
Disaggregation of Revenue
Operating revenue	$ (53,315)	$ (22,402)