GOODWILL AND INTANGIBLE ASSETS - Goodwill (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2022 USD ($)
Goodwill by reportable operating segment
Balance at the beginning of the period	$ 300,337
Purchase accounting adjustment	6,915
Balance at the end of the period	307,252
ArcBest
Goodwill by reportable operating segment
Balance at the beginning of the period	299,707
Purchase accounting adjustment	6,915
Balance at the end of the period	306,622
FleetNet
Goodwill by reportable operating segment
Balance at the beginning of the period	630
Balance at the end of the period	$ 630