OPERATING SEGMENT DATA - Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
OPERATING INCOME
Operating income	$ 94,928	$ 32,191
OTHER INCOME (COSTS)
Interest and dividend income	106	392
Interest and other related financing costs	(1,939)	(2,428)
Other, net	(826)	1,192
Total other costs	(2,659)	(844)
INCOME BEFORE INCOME TAXES	92,269	31,347
Operating Segments | Asset Based
OPERATING INCOME
Operating income	80,034	30,055
Operating Segments | ArcBest
OPERATING INCOME
Operating income	21,116	8,265
Operating Segments | FleetNet
OPERATING INCOME
Operating income	1,717	1,023
Other and eliminations
OPERATING INCOME
Operating income	$ (7,939)	$ (7,152)