OPERATING SEGMENT DATA - Revenue from customers (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Revenues
Revenues	$ 1,392,929	$ 948,973	$ 2,728,003	$ 1,778,186
Asset Based
Revenues
Revenues	788,973	630,145	1,464,491	1,159,869
ArcBest
Revenues
Revenues	538,780	268,038	1,130,502	518,279
FleetNet
Revenues
Revenues	68,204	49,951	135,187	98,385
Corporate and Other
Revenues
Revenues	(3,028)	839	(2,177)	1,653
Operating Segments | Asset Based
Revenues
Revenues	802,622	652,832	1,507,933	1,209,124
Operating Segments | ArcBest
Revenues
Revenues	549,655	270,748	1,144,939	523,084
Operating Segments | FleetNet
Revenues
Revenues	82,132	59,547	160,510	118,710
Intersegment revenues
Revenues
Revenues	(38,452)	(34,993)	(83,202)	(74,385)
Intersegment revenues | Asset Based
Revenues
Revenues	13,649	22,687	43,442	49,255
Intersegment revenues | ArcBest
Revenues
Revenues	10,875	2,710	14,437	4,805
Intersegment revenues | FleetNet
Revenues
Revenues	13,928	9,596	25,323	20,325
Other and eliminations
Revenues
Revenues	$ (41,480)	$ (34,154)	$ (85,379)	$ (72,732)