REVENUE RECOGNITION - Disaggregation of Revenue by Type (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Disaggregation of Revenue
Revenues	$ 123,737	$ 133,622	$ 250,510	$ 267,596
Contract assets	1,400		1,400		$ 900
Intersegment Eliminations
Disaggregation of Revenue
Revenues	(3,628)	(2,429)	(6,674)	(4,807)
Trucking
Disaggregation of Revenue
Revenues	87,920	96,069	180,921	190,609
Trucking | Operating Segments
Disaggregation of Revenue
Revenues	88,627	96,476	182,622	191,378
Trucking | Intersegment Eliminations
Disaggregation of Revenue
Revenues	(707)	(407)	(1,701)	(769)
USAT Logistics
Disaggregation of Revenue
Revenues	35,817	37,553	69,589	76,987
USAT Logistics | Operating Segments
Disaggregation of Revenue
Revenues	38,738	39,575	74,562	81,025
USAT Logistics | Intersegment Eliminations
Disaggregation of Revenue
Revenues	(2,921)	(2,022)	(4,973)	(4,038)
Freight
Disaggregation of Revenue
Revenues	110,093	115,153	219,970	230,994
Freight | Intersegment Eliminations
Disaggregation of Revenue
Revenues	(3,461)	(2,209)	(6,154)	(4,420)
Freight | Trucking | Operating Segments
Disaggregation of Revenue
Revenues	78,514	82,664	159,417	164,086
Freight | USAT Logistics | Operating Segments
Disaggregation of Revenue
Revenues	35,040	34,698	66,707	71,328
Fuel surcharge
Disaggregation of Revenue
Revenues	10,534	16,901	24,546	32,341
Fuel surcharge | Intersegment Eliminations
Disaggregation of Revenue
Revenues	(167)	(220)	(520)	(387)
Fuel surcharge | Trucking | Operating Segments
Disaggregation of Revenue
Revenues	8,083	13,034	19,371	24,799
Fuel surcharge | USAT Logistics | Operating Segments
Disaggregation of Revenue
Revenues	2,618	4,087	5,695	7,929
Accessorial
Disaggregation of Revenue
Revenues	3,110	1,568	5,994	4,261
Accessorial | Trucking | Operating Segments
Disaggregation of Revenue
Revenues	2,030	778	3,834	2,493
Accessorial | USAT Logistics | Operating Segments
Disaggregation of Revenue
Revenues	$ 1,080	$ 790	$ 2,160	$ 1,768