REVENUE RECOGNITION - Disaggregation of Revenue by Type (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue
Revenues	$ 126,773	$ 133,974
Contract assets	1,300	900
Intersegment Eliminations
Disaggregation of Revenue
Revenues	(3,046)	(2,377)
Trucking
Disaggregation of Revenue
Revenues	93,000	94,561
Trucking | Operating Segments
Disaggregation of Revenue
Revenues	93,994	94,902
Trucking | Intersegment Eliminations
Disaggregation of Revenue
Revenues	(994)	(341)
USAT Logistics
Disaggregation of Revenue
Revenues	33,773	39,413
USAT Logistics | Operating Segments
Disaggregation of Revenue
Revenues	35,825	41,449
USAT Logistics | Intersegment Eliminations
Disaggregation of Revenue
Revenues	(2,052)	(2,036)
Freight
Disaggregation of Revenue
Revenues	109,696	115,843
Freight | Intersegment Eliminations
Disaggregation of Revenue
Revenues	(2,874)	(2,210)
Freight | Trucking | Operating Segments
Disaggregation of Revenue
Revenues	80,903	81,423
Freight | USAT Logistics | Operating Segments
Disaggregation of Revenue
Revenues	31,667	36,630
Fuel surcharge
Disaggregation of Revenue
Revenues	14,192	15,440
Fuel surcharge | Intersegment Eliminations
Disaggregation of Revenue
Revenues	(172)	(167)
Fuel surcharge | Trucking | Operating Segments
Disaggregation of Revenue
Revenues	11,287	11,765
Fuel surcharge | USAT Logistics | Operating Segments
Disaggregation of Revenue
Revenues	3,077	3,842
Accessorial
Disaggregation of Revenue
Revenues	2,885	2,691
Accessorial | Intersegment Eliminations
Disaggregation of Revenue
Revenues	0	0
Accessorial | Trucking | Operating Segments
Disaggregation of Revenue
Revenues	1,804	1,714
Accessorial | USAT Logistics | Operating Segments
Disaggregation of Revenue
Revenues	$ 1,081	$ 977