REVENUE RECOGNITION - Disaggregation of Revenue by Type (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Disaggregation of Revenue
Revenues	$ 158,505	$ 126,773
Contract assets	2,600		$ 1,100
Intersegment Eliminations
Disaggregation of Revenue
Revenues	(12,979)	(3,046)
Trucking
Disaggregation of Revenue
Revenues	102,776	93,000
Trucking | Operating Segments
Disaggregation of Revenue
Revenues	103,103	93,994
Trucking | Intersegment Eliminations
Disaggregation of Revenue
Revenues	(327)	(994)
USAT Logistics
Disaggregation of Revenue
Revenues	55,729	33,773
USAT Logistics | Operating Segments
Disaggregation of Revenue
Revenues	68,381	35,825
USAT Logistics | Intersegment Eliminations
Disaggregation of Revenue
Revenues	(12,652)	(2,052)
Freight
Disaggregation of Revenue
Revenues	140,873	109,696
Freight | Intersegment Eliminations
Disaggregation of Revenue
Revenues	(12,604)	(2,874)
Freight | Trucking | Operating Segments
Disaggregation of Revenue
Revenues	91,015	80,903
Freight | USAT Logistics | Operating Segments
Disaggregation of Revenue
Revenues	62,462	31,667
Fuel Surcharge
Disaggregation of Revenue
Revenues	14,240	14,192
Fuel Surcharge | Intersegment Eliminations
Disaggregation of Revenue
Revenues	(375)	(172)
Fuel Surcharge | Trucking | Operating Segments
Disaggregation of Revenue
Revenues	10,319	11,287
Fuel Surcharge | USAT Logistics | Operating Segments
Disaggregation of Revenue
Revenues	4,296	3,077
Accessorial
Disaggregation of Revenue
Revenues	3,392	2,885
Accessorial | Trucking | Operating Segments
Disaggregation of Revenue
Revenues	1,769	1,804
Accessorial | USAT Logistics | Operating Segments
Disaggregation of Revenue
Revenues	$ 1,623	$ 1,081