SEGMENT REPORTING - Segment Reporting Information by Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information
Operating revenue	$ 551,138	$ 522,631
Operating income	12,858	2,315
Depreciation and amortization	41,359	37,193
Trucking
Segment Reporting Information
Operating revenue	381,589	375,657
Depreciation and amortization	40,203	36,245
USAT Logistics
Segment Reporting Information
Operating revenue	169,549	146,974
Depreciation and amortization	1,156	948
Operating Segments
Segment Reporting Information
Operating income	12,858	2,315
Operating Segments | Trucking
Segment Reporting Information
Operating revenue	384,256	377,093
Operating income	9,297	(447)
Operating Segments | USAT Logistics
Segment Reporting Information
Operating revenue	191,951	154,011
Operating income	3,561	2,762
Intersegment Eliminations
Segment Reporting Information
Operating revenue	(25,069)	(8,473)
Intersegment Eliminations | Trucking
Segment Reporting Information
Operating revenue	(2,667)	(1,436)
Intersegment Eliminations | USAT Logistics
Segment Reporting Information
Operating revenue	(22,402)	(7,037)
Foreign Countries | Operating Segments | Trucking
Segment Reporting Information
Operating revenue	$ 33,600	$ 37,000